Compositions for increasing half-life of a therapeutic agent in canines and methods of use

ABSTRACT

Provided are compositions for increasing the half-life of a polypeptide or polypeptides in a canine and methods of their use. The compositions involve variant canine IgG Fc regions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/861,077, filed Apr. 28, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/733,105, filed Jan. 2, 2020, which claims thebenefit of priority of U.S. Provisional Application No. 62/788,035,filed Jan. 3, 2019, the contents of which are incorporated by referenceherein in its entirety.

SEQUENCE LISTING

The present application contains a Sequence Listing which has beensubmitted in XML format and is hereby incorporated by reference in itsentirety. Said XML copy, created on Dec. 2, 2022, is named51682-002004_Sequence_Listing_12_2_22 and is 29,878 bytes in size.

FIELD

This disclosure relates generally to polypeptides (e.g., fusionpolypeptides such as polypeptide-Fc region fusions; or binding moleculessuch as antibodies or ligand-binding portions of receptor-Fc fusions)that have increased half-life in canines compared to their wild typecounterparts.

BACKGROUND

The Fc region of antibodies plays a number of functional roles,including, but not limited to, protecting the antibody from degradationthrough the lysosomal pathway and mediating antibody effector functions.With the increasing use of canine antibodies as therapeutic agents,there has been an enhanced focus on not just selecting an optimal Fab,but also combining it with an appropriate Fc for desired half-life andeffector functions.

There is little guidance in the art relating to increasing half-life ofpolypeptide therapeutics (e.g., antibodies) for use in dogs. Thisdisclosure remedies that failing by providing Fc region variants thatimprove the serum persistence of polypeptides (e.g., antibodies) incanines.

SUMMARY

Provided herein is a platform technology relating to canine CH2, CH3 andFc sequences that are useful in therapeutic polypeptides. Thisdisclosure features polypeptides that have increased binding to canineFcRn than control polypeptides (e.g., the wild type counterpart IgGcanine Fc regions). In some instances, these polypeptides have increasedbinding to canine FcRn than control polypeptides at any pH (e.g., at anypH between about 5.0 to about 8.0). In some instances, thesepolypeptides have increased binding to canine FcRn than controlpolypeptides at pH 5.5 and/or pH 6.5. In some instances, thesepolypeptides can, e.g., bind to canine FcRn at a higher level at acidicpH (e.g., pH 5.5 or pH6.5) than at a neutral pH (e.g., pH 7.0, 7.1, 7.2,7.3, 7.4, or 7.5). In some instances, these polypeptides bind to canineFcRn at a higher level at pH 5.5 than at pH 7.4. This disclosurerelates, in part, to polypeptides that have increased half-life incanines than their wild type counterparts. For example, provided arebinding molecules (e.g., antibodies or ligand-binding portions ofreceptors) with increased half-life relative to versions of thesebinding molecules not attached to the Fc regions (e.g., CH2, CH3, orCH2+CH3 regions) disclosed herein. Also provided are enzyme-Fc regionfusions, ligand-Fc region fusions, and peptide-Fc region fusions,wherein the fusions have increased half-life compared with their wildtype counterparts. The Fc regions, in addition to having a substitutionor substitutions (relative to the wild type canine Fc region) thatincrease half-life may also include other substitutions that, e.g.,increase effector function, decrease effector function, and/or decreaseheterogeneity of the polypeptide (e.g., by removing one or morepost-translational modifications in the Fc region). The canine CH2, CH3,and Fc region sequences can be from any canine antibody. In someinstances, the canine CH2, CH3, and Fc region sequences are from acanine IgG (e.g., IgG.A, IgG.B, IgG.C, or IgG.D).

The disclosure features a recombinant protein comprising (1) a bindingdomain, or a fragment thereof, that specifically binds to a ligand, oran epitope of a protein, wherein the binding domain is attached to (2) adomain comprising a CH2 region, a CH3 region, or an Fc region (CH2+CH3region) disclosed herein. In some instances, the binding domaincomprises (i) the six complementarity determining regions (CDRs) of acanine or human/humanized antibody; (ii) the VH and/or VL of a canine,caninized, humanized, or human antibody; (iii) a nanobody; (iv) a scFv;(v) an Fab; or (vi) a soluble receptor-binding domain that binds aligand, or a ligand-binding fragment thereof.

The disclosure also provides a composition comprising: (1) a firstpolypeptide comprising a first Fc region (e.g., a CH2 region, a CH3region, a CH2+CH3 region) comprising a canine IgG Fc region variantdescribed herein; and (2) a second polypeptide comprising a second Fcregion comprising a canine IgG Fc region variant described herein. Thefirst and second polypeptide can be associated through the first andsecond Fc regions. In some instances, the amino acid sequences of thefirst and second Fc regions are the same. In other instances, the aminoacid sequences of the first and second Fc regions are different (e.g.,by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 21, 22, 23, 24, or 25 amino acids). In some instances, the Fc regionvariant is a variant of a canine IgG.B antibody Fc region. In someinstances, the Fc region variant is a variant of a canine IgG.A antibodyFc region. In some instances, the Fc region variant is a variant of acanine IgG.C antibody Fc region. In some instances, the Fc regionvariant is a variant of a canine IgG.D antibody Fc region.

Also disclosed is a fusion molecule comprising a canine IgG Fc regionvariant disclosed herein and a polypeptide. In some embodiments, thecanine IgG Fc region variant is covalently attached to the polypeptide(e.g., through a hinge region or a linker). In some instances, thepolypeptide is a ligand binding domain of a canine receptor protein, anextracellular domain of a canine receptor protein, or an antigen-bindingdomain. In some instances, the polypeptide is selected from the ligandbinding domain or extracellular domain of canine IL-13Rα1, or IL-13Ra2,canine EPO, canine CTLA4, canine LFA3, canine VEGFR1/VEGFR3, canineIL-1R, canine GLP-1 receptor agonist, and canine Thrombopoietin bindingpeptide. In some instances, the polypeptide is a scFv, a nanobody, orsingle domain antibody. In some instances, the IgG Fc region variant isa variant of a canine IgG.B antibody Fc region. In some instances, theIgG Fc region variant is a variant of a canine IgG.A antibody Fc region.In some instances, the IgG Fc region variant is a variant of a canineIgG.C antibody Fc region. In some instances, the IgG Fc region variantis a variant of a canine IgG.D antibody Fc region.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc CH2 region variant, the CH2 region variantcomprising an amino acid sequence that is at least 75% identical to thesequence set forth in SEQ ID NO:1, and comprises at least one of thefollowing:

-   -   an amino acid other than Ile at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Arg at amino acid position 252,    -   an amino acid other than Thr at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than His at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Glu at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311, or    -   an amino acid other than Thr at amino acid position 315.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc CH2 region in place of the IgG FcCH2 region variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptide or polypeptides; and wherein the amino acidpositions are based on EU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:1.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc CH2 region variant, the CH2 region variantcomprising an amino acid sequence that is at least 75% identical to thesequence set forth in SEQ ID NO:2, and comprises at least one of thefollowing:

-   -   an amino acid other than Thr at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Leu at amino acid position 252,    -   an amino acid other than Ala at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than Gln at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Gly at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311, or    -   an amino acid other than Lys at amino acid position 315.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc CH2 region in place of the IgG FcCH2 region variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptide or polypeptides; and wherein the amino acidpositions are based on EU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:2.

In one aspect, the disclosure further provides a polypeptide orpolypeptides comprising a canine IgG Fc CH2 region variant, the CH2region variant comprising an amino acid sequence that is at least 75%identical to the sequence set forth in SEQ ID NO:3, and comprises atleast one of the following:

-   -   an amino acid other than Ile at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Val at amino acid position 252,    -   an amino acid other than Ala at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than Gln at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Gly at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311, or    -   an amino acid other than Ser at amino acid position 315,

In some embodiments, the polypeptide or polypeptides has/have: increasedhalf-life in a dog than a control polypeptide or control polypeptides,wherein the control polypeptide or control polypeptides are identical tothe polypeptide or polypeptides except for having the corresponding wildtype canine IgG Fc CH2 region in place of the IgG Fc CH2 region variant.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:3.

In one aspect, the disclosure is related to a polypeptide orpolypeptides comprising a canine IgG Fc CH2 region variant, the CH2region variant comprising an amino acid sequence that is at least 75%identical to the sequence set forth in SEQ ID NO:4, and comprises atleast one of the following:

-   -   an amino acid other than Ile at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Arg at amino acid position 252,    -   an amino acid other than Thr at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than His at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Glu at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311, or    -   an amino acid other than Thr at amino acid position 315.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc CH2 region in place of the IgG FcCH2 region variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptide or polypeptides; and wherein the amino acidpositions are based on EU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:4.

In some embodiments, the polypeptide or polypeptides comprise(s) atleast one of the following:

-   -   Glu or Gln at amino acid position 250,    -   Asp or Glu at amino acid position 251,    -   Tyr at amino acid position 252,    -   Thr at amino acid position 254,    -   Asp, Glu, or Phe at amino acid position 256,    -   Asn or Asp at amino acid position 285,    -   Asp at amino acid position 286,    -   Arg, Gln, or Ala at amino acid position 307,    -   Pro at amino acid position 308,    -   Pro at amino acid position 309,    -   Val at amino acid position 311, or    -   Asp at amino acid position 315.

In some embodiments, the polypeptide or polypeptides comprise(s) atleast one of the following:

-   -   Tyr or Met at amino acid position 252,    -   Thr at amino acid position 254, or    -   Glu at amino acid position 256.

In some embodiments, the canine IgG Fc CH2 region variant comprises atleast one of the following:

-   -   (i) Tyr at amino acid position 252, Thr at amino acid position        254, and Glu at amino acid position 256;    -   (ii) Leu at amino acid position 428 and Ser at amino acid        position 434;    -   (iii) Asp at amino acid position 256, Arg at amino acid position        307, and Val at amino acid position 311;    -   (iv) Asp at amino acid position 256, Asp at amino acid position        315, and Val at amino acid position 378;    -   (v) Asp at amino acid position 256, Asp at amino acid position        286, Arg at amino acid position 307, and Val at amino acid        position 311;    -   (vi) Asn at amino acid position 285, Gln at amino acid position        307, and Asp at amino acid position 315; or    -   (vii) Asp at amino acid position 251, and Pro at amino acid        position 309.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc CH3 region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:5, and comprises at least one of the following:

-   -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than Gln at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc CH3 region in place of the IgG FcCH3 region variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptide or polypeptides; and wherein the amino acidpositions are based on EU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:5.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc CH3 region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:6, and comprises at least one of the following:

-   -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than His at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc CH3 region in place of the IgG FcCH3 region variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptide or polypeptides; and wherein the amino acidpositions are based on EU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:6.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc CH3 region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:7, and comprises at least one of the following:

-   -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than His at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: increasedhalf-life in a dog than a control polypeptide or control polypeptides,wherein the control polypeptide or control polypeptides are identical tothe polypeptide or polypeptides except for having the corresponding wildtype canine IgG Fc CH3 region in place of the IgG Fc CH3 region variant.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:7.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc CH3 region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:8, and comprises at least one of the following:

-   -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than Gln at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc CH3 region in place of the IgG FcCH3 region variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptide or polypeptides; and wherein the amino acidpositions are based on EU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:8.

In some embodiments, the polypeptide or polypeptides comprise(s) atleast one of the following:

-   -   Val at amino acid position 378,    -   Ala at amino acid position 380,    -   Leu at amino acid position 428,    -   Ala or Lys at amino acid position 430,    -   Lys at amino acid position 433,    -   Ser, Ala, or Phe at amino acid position 434,    -   Try at amino acid position 435,    -   His at amino acid position 436.    -   In some embodiments, the canine IgG Fc CH3 region variant        comprises:    -   (i) Leu at amino acid position 428, and Ser at amino acid        position 434;    -   (ii) Leu at amino acid position 428, and Ala at amino acid        position 434;    -   (iii) Lys at amino acid position 430, and Lys at amino acid        position 433; or    -   (iv) Tyr at amino acid position 435, and His at amino acid        position 436.

In some embodiments, the polypeptide or polypeptides comprise(s) Tyr,Trp, Arg, or His at amino acid position 434.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:9, and that comprises at least one of the following:

-   -   an amino acid other than Ile at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Arg at amino acid position 252,    -   an amino acid other than Thr at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than His at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Glu at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311,    -   an amino acid other than Thr at amino acid position 315,    -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than Gln at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc region in place of the IgG Fcregion variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptides; and wherein the amino acid positions are based onEU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:9.

In one aspect, the disclosure also provides a polypeptide orpolypeptides comprising a canine IgG Fc region variant comprising anamino acid sequence that is at least 75% identical to the sequence setforth in SEQ ID NO:10, and that comprises at least one of the following:

-   -   an amino acid other than Thr at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Leu at amino acid position 252,    -   an amino acid other than Ala at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than Gln at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Gly at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311,    -   an amino acid other than Lys at amino acid position 315,    -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than His at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc region in place of the IgG Fcregion variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptides; and wherein the amino acid positions are based onEU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:10.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:11, and that comprises at least one of the following:

-   -   an amino acid other than Ile at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Val at amino acid position 252,    -   an amino acid other than Ala at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than Gln at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Gly at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311,    -   an amino acid other than Ser at amino acid position 315,    -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than His at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: increasedhalf-life in a dog than a control polypeptide or control polypeptides,wherein the control polypeptide or control polypeptides are identical tothe polypeptide or polypeptides except for having the corresponding wildtype canine IgG Fc region in place of the IgG Fc region variant.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:11.

In one aspect, the disclosure provides a polypeptide or polypeptidescomprising a canine IgG Fc region variant comprising an amino acidsequence that is at least 75% identical to the sequence set forth in SEQID NO:12, and that comprises at least one of the following:

-   -   an amino acid other than Ile at amino acid position 250,    -   an amino acid other than Leu at amino acid position 251,    -   an amino acid other than Arg at amino acid position 252,    -   an amino acid other than Thr at amino acid position 254,    -   an amino acid other than Thr at amino acid position 256,    -   an amino acid other than His at amino acid position 285,    -   an amino acid other than Thr at amino acid position 286,    -   an amino acid other than Pro at amino acid position 307,    -   an amino acid other than Ile at amino acid position 308,    -   an amino acid other than Glu at amino acid position 309,    -   an amino acid other than Gln at amino acid position 311,    -   an amino acid other than Thr at amino acid position 315,    -   an amino acid other than Asp at amino acid position 378,    -   an amino acid other than Glu at amino acid position 380,    -   an amino acid other than Met at amino acid position 428,    -   an amino acid other than Glu at amino acid position 430,    -   an amino acid other than Gln at amino acid position 433,    -   an amino acid other than Asn at amino acid position 434,    -   an amino acid other than His at amino acid position 435, or    -   an amino acid other than Tyr at amino acid position 436.

In some embodiments, the polypeptide or polypeptides has/have: (1)increased half-life in a dog than a control polypeptide or controlpolypeptides, wherein the control polypeptide or control polypeptidesare identical to the polypeptide or polypeptides except for having thecorresponding wild type canine IgG Fc region in place of the IgG Fcregion variant; and/or (2) increased binding to canine FcRn than thecontrol polypeptides; and wherein the amino acid positions are based onEU numbering.

In some embodiments, the amino acid sequence is at least 80%, at least85%, at least 90%, at least 95%, at least 96%, at least 97%, at least98%, at least 99%, or 100% identical to the sequence set forth in SEQ IDNO:12.

In some embodiments, the polypeptide or polypeptides comprise at leastone of the following:

-   -   Glu or Gln at amino acid position 250,    -   Asp or Glu at amino acid position 251,    -   Tyr at amino acid position 252,    -   Thr at amino acid position 254,    -   Asp, Glu, or Phe at amino acid position 256,    -   Asn or Asp at amino acid position 285,    -   Asp at amino acid position 286,    -   Arg, Gln, or Ala at amino acid position 307,    -   Pro at amino acid position 308,    -   Pro at amino acid position 309,    -   Val at amino acid position 311,    -   Asp at amino acid position 315,    -   Val at amino acid position 378,    -   Ala at amino acid position 380,    -   Leu at amino acid position 428,    -   Ala or Lys at amino acid position 430,    -   Lys at amino acid position 433,    -   Ser, Ala, or Phe at amino acid position 434,    -   Try at amino acid position 435, or    -   His at amino acid position 436.

In some embodiments, the polypeptide or polypeptides comprise(s) atleast one of the following:

-   -   Tyr or Met at amino acid position 252,    -   Thr at amino acid position 254,    -   Glu at amino acid position 256, or    -   Tyr, Trp, Arg, or His at amino acid position 434.

In some embodiments, the canine IgG Fc region variant comprises at leastone of the following:

-   -   (i) Tyr at amino acid position 252, Thr at amino acid position        254, and Glu at amino acid position 256;    -   (ii) Leu at amino acid position 428 and Ser at amino acid        position 434;    -   (iii) Asp at amino acid position 256, Arg at amino acid position        307, and Val at amino acid position 311;    -   (iv) Asp at amino acid position 256, Asp at amino acid position        315, and Val at amino acid position 378;    -   (v) Asp at amino acid position 256, Asp at amino acid position        286, Arg at amino acid position 307, and Val at amino acid        position 311;    -   (vi) Asn at amino acid position 285, Gln at amino acid position        307, and Asp at amino acid position 315;    -   (vii) Asp at amino acid position 256, Arg at amino acid position        307, Val at amino acid position 311, and Val at amino acid        position 378;    -   (viii) Asp at amino acid position 285, Val at amino acid        position 311, and Val at amino acid position 378;    -   (ix) Asp at amino acid position 256, Asp at amino acid position        285, and Val at amino acid position 378;    -   (x) Asp at amino acid position 256, Val at amino acid position        311, and Val at amino acid position 378;    -   (xi) Asp at amino acid position 256, Asp at amino acid position        285, Asp at amino acid position 286, Arg at amino acid position        307, and Val at amino acid position 378;    -   (xii) Asp at amino acid position 256, Asp at amino acid position        286, Arg at amino acid position 307, Val at amino acid position        311, and Val at position 378;    -   (xiii) Gln at amino acid position 307, Val at amino acid        position 311, and Val at amino acid position 378;    -   (xiv) Asp at amino acid position 285, Gln at amino acid position        307, and Val at amino acid position 378;    -   (xv) Asp at amino acid position 256, Asp at amino acid position        285, Arg at amino acid position 307, Val at amino acid position        311, and Val at amino acid position 378;    -   (xvi) Gln at amino acid position 307, Ala at amino acid position        380, Ser or Ala at amino acid position 434;    -   (xvii) Leu at amino acid position 428, and Ser or Ala at amino        acid position 434; or    -   (xviii) Gln at amino acid position 250 and Leu at amino acid        position 428.

In some embodiments, the polypeptide or polypeptides is/are an antigenbinding domain(s).

In some embodiments, the antigen binding domain(s) bind to an antigenselected from the group consisting of NGF, TrKA, ADAMTS, IL-1, IL-2,IL-4, IL-4R, Angiotensin type 1 (AT1) receptor, Angiotensin type 2 (AT2)receptor, IL-5, IL-12, IL-13, IL-31, IL-33, TNF-alpha, IgE, PD-1, PD-1ligand, CD3, CD20, CD47, CD52, OX40, OX40 ligand, CTLA4, VEGF, EGFR, NAV1.7, and complement system complex (e.g., C1 complex, C2 complex, C3complex, C4 complex, C5 complex, C6 complex, C7 complex, C8 complex, C9complex).

In some embodiments, the antigen binding domain(s) is/are a scFv, scFab,or nanobody.

In some embodiments, the polypeptide or polypeptides described hereinfurther comprise a protein. In some embodiments, the protein is selectedfrom the group consisting of EPO, CTLA4, LFA3, VEGFR1/VEGFR3, IL-1R,IL-4R, GLP-1 receptor agonist, and Thrombopoietin binding peptide.

In one aspect, the disclosure provides a pharmaceutical compositioncomprising (i) the polypeptide or polypeptides described herein, and(ii) a pharmaceutically acceptable excipient.

In one aspect, the disclosure provides a nucleic acid or nucleic acidsencoding the polypeptide or polypeptides described herein.

In one aspect, the disclosure provides an expression vector orexpression vectors comprising the nucleic acid or nucleic acidsdescribed herein.

In one aspect, the disclosure provides a host cell comprising thenucleic acid or nucleic acids described herein or the expression vectoror expression vectors described herein.

In one aspect, the disclosure provides a method of making a polypeptideor polypeptides, the method comprising

-   -   (a) providing a nucleic acid or nucleic acids described herein;    -   (b) expressing the nucleic acid or nucleic acids in a host cell        culture, thereby producing the polypeptide or polypeptides; and    -   (c) collecting the polypeptide or polypeptides produced in (b)        from the host cell culture.

In some embodiments, the method further comprises formulating thepolypeptide or polypeptides as a pharmaceutical formulation.

In one aspect, the disclosure provides a method of treating a caninedisease or disorder in a dog in need thereof, the method comprisingadministering an effective amount of a composition comprising thepharmaceutical composition described herein to the dog.

In one aspect, the disclosure provides a method of preventing a caninedisease or disorder in a dog in need thereof, the method comprisingadministering an effective amount of a composition comprising thepharmaceutical composition described herein to the dog.

In some embodiments, the disease or disorder is an allergic disease, achronic pain, an acute pain, an inflammatory disease, an autoimmunedisease, an endocrine disease, a gastrointestinal disease, acardiovascular disease, a renal disease, a fertility related disorder,an infectious disease or a cancer.

In some embodiments, the disease or disorder is atopic dermatitis,allergic dermatitis, osteoarthritic pain, arthritis, anemia, or obesity.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, the exemplary methods andmaterials are described below. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety. In case of conflict, the presentapplication, including definitions, will control. The materials,methods, and examples are illustrative only and not intended to belimiting.

Other features and advantages of the invention will be apparent from thefollowing detailed description and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an amino acid sequence alignment of canine IgG γchains. Thesechains contain VH, CH1, CH2, and CH3 domains and the hinge regionbetween CH1 and CH2. An N-glycosylation site is shown in bold and markedin a block. These sequences are assigned SEQ ID NOs.: 13, 14, 15, and16, respectively.

FIG. 2 is an amino acid sequence alignment of the CH2 region of canineIgG γchains. These sequences are assigned SEQ ID NOs.: 1, 2, 3, and 4,respectively. Residues that are substituted to increase half-life areidentified by underlines.

FIG. 3 is an amino acid sequence alignment of the CH3 region of canineIgG γchains. These sequences are assigned SEQ ID NOs.: 5, 6, 7, and 8,respectively. Residues that are substituted to increase half-life areidentified by underlines.

FIG. 4 is an amino acid sequence alignment of the Fc region of canineIgG γchains. These sequences are assigned SEQ ID NOs.: 9, 10, 11, and12, respectively. Residues that are substituted to increase half-lifeare identified by underlines.

FIG. 5 is a table provided EU numbering for the CH2 region of canineIgG.

FIG. 6 is a table provided EU numbering for the CH3 region of canineIgG.

FIGS. 7A-7U depict Biacore sensorgrams from the alanine scanningmutagenesis experiment. The lighter line on each figure represents themeasured data and the darker line represents the fitted curve using a1:1 interaction model.

FIGS. 8A-8C depict Biacore sensorgrams for wild type and the differentvariants from the NNK libraries at position 250. The lighter line oneach figure represents the measured data and the darker line is thefitted curve using a 1:1 interaction model.

FIGS. 9A-9C depict Biacore sensorgrams for wild type and the differentvariants from the NNK libraries at position 252. The lighter line oneach figure represents the measured data and the darker line is thefitted curve using a 1:1 interaction model.

FIGS. 10A and 10B depict Biacore sensorgrams for wild type and thevariant A254T. The lighter line represents the measured data and thedarker line represents the fitted curve using a 1:1 interaction model.

FIGS. 11A and 11B depict Biacore sensorgrams for wild type and thevariant G309P. The lighter line represents the measured data and thedarker line represents the fitted curve using a 1:1 interaction model.

FIGS. 12A and 12B depict Biacore sensorgrams for wild type and thevariant Q311V. The lighter line represents the measured data and thedarker line represents the fitted curve using a 1:1 interaction model.

FIGS. 13A and 13B depict Biacore sensorgrams for wild type and thevariant D378V. The lighter line represents the measured data and thedarker line represents the fitted curve using a 1:1 interaction model.

FIGS. 14A and 14B depict Biacore sensorgrams for wild type and thevariant E380A. The lighter line represents the measured data and thedarker line represents the fitted curve using a 1:1 interaction model.

FIGS. 15A-15F depict Biacore sensorgrams for wild type and the differentvariants from the NNK libraries at position 434. The lighter linerepresents the measured data and the darker line represents the fittedcurve using a 1:1 interaction model.

FIGS. 16A-16E depict Biacore sensorgrams for different variants in aconcentration series. The concentration of canine FcRn used were 100 nM(white circle), 200 nM (black circle), 400 nM (black triangle), and 800nM (white triangle). The lighter line on each figure is the measureddata and the darker line is the fitted curve using a 1:1 interactionmodel.

DETAILED DESCRIPTION

With the increasing use of polypeptide (e.g., antibodies, ligand-bindingdomains of receptors, enzymes, ligands, peptides) as therapeutics forthe prevention and treatment of a wide variety of canine diseases, it isimportant to develop polypeptides with extended half-life, especially inthe context of the prevention or treatment of chronic diseases in whicha polypeptide must be administered repetitively.

Accordingly, this disclosure features canine immunoglobulin CH2, CH3,and Fc regions comprising mutations that enhance the half-life of apolypeptide or polypeptides comprising these sequences. Also disclosedare polypeptides comprising these domains and methods of their use.These peptides can be used for various therapeutic and diagnosticpurposes.

Canine Antibodies

Dogs have four IgG heavy chains referred to as A, B, C, and D. Theseheavy chains represent four different subclasses of dog IgG, which arereferred to as IgG.A, IgG.B, IgG.C and IgG.D. The amino acid and DNAsequences for these heavy chains are available from Tang et al., Vet.Immunol. Immunopathol., 80: 259-270 (2001) and the GENBANK database. Forexample, the amino acid sequence of IgG.A heavy chain has GENBANKaccession number AAL35301.1, IgG.B has GENBANK accession numberAAL35302.1, IgG.C has GENBANK accession number AAL35303.1, and IgG.D hasGENBANK accession number AAL35304.1. Canine antibodies also include twotypes of light chains: kappa and lambda. The DNA and amino acid sequenceof these light chains can also be obtained from GENBANK database. Forexample, the dog kappa light chain amino acid sequence has accessionnumber ABY 57289.1 and the dog lambda light chain has accession numberABY 55569.1.

CH2 Region of a Canine Fc region:

The CH2 region of a canine antibody comprises or consists of amino acids237 to 340 (according to EU numbering) of a canine IgG antibody. It isto be understood that the CH2 region may include one to six (e.g., 1, 2,3, 4, 5, 6) additional amino acids or deletions at their N and/orC-terminus.

The amino acid sequence of the CH2 region of canine IgG.A is providedbelow:

(SEQ ID NO: 1) GPSVLI FPPKPKDILR ITRTPEVTCV VLDLGREDPEVQISWFVDGK EVHTAKTQSR EQQFNGTYRV VSVLPIEHQDWLTGKEFKCR VNHIDLPSPI ERTISKAR

The amino acid sequence of the CH2 domain of canine IgG.B is providedbelow:

(SEQ ID NO: 2) GPSVFIFPPK PKDTLLIART PEVTCVVVDL DPEDPEVQISWFVDGKQMQT AKTQPREEQF NGTYRVVSVL PIGHQDWLKG KQFTCKVNNK ALPSPIERTI SKAR

The amino acid sequence of the CH2 domain of canine IgG.C is providedbelow:

(SEQ ID NO: 3) GPSVFIFPP KPKDILVTAR TPTVTCVVVD LDPENPEVQISWFVDSKQVQ TANTQPREEQ SNGTYRVVSV LPIGHQDWLS GKQFKCKVNN KALPSPIEEI ISKTP 

The amino acid sequence of the CH2 domain of canine IgG.D is providedbelow:

(SEQ ID NO: 4) GPSV FIFPPKPKDI LRITRTPEIT CVVLDLGREDPEVQISWFVD GKEVHTAKTQ PREQQFNSTY RVVSVLPIEHQDWLTGKEFK CRVNHIGLPS PIERTISKARCH3 Region of a Canine Fc region:

The CH3 region of a canine antibody comprises or consists of amino acids345 to 447 (according to EU numbering) of a canine IgG antibody. It isto be understood that the CH3 region may include one to six (e.g., 1, 2,3, 4, 5, 6) additional amino acids or deletions at their N and/orC-terminus.

The amino acid sequence of the CH3 domain of canine IgG.A is providedbelow:

(SEQ ID NO: 5) KPSVYVLP PSPKELSSSD TVSITCLIKD FYPPDIDVEWQSNGQQEPER KHRMTPPQLD EDGSYFLYSK LSVDKSRWQQGDPFTCAVMH ETLQNHYTDL SLSHSPGK

The amino acid sequence of the CH3 domain of canine IgG.B is providedbelow:

(SEQ ID NO: 6) QP SVYVLPPSRE ELSKNTVSLT CLIKDFFPPDIDVEWQSNGQ QEPESKYRTT PPQLDEDGSY FLYSKLSVDK SRWQRGDTFI CAVMHEALHNHYTQESLSHS PGK

The amino acid sequence of the CH3 domain of canine IgG.C is providedbelow:

(SEQ ID NO: 7) Q PNVYVLPPSR DEMSKNTVTL TCLVKDFFPPEIDVEWQSNG QQEPESKYRM TPPQLDEDGS YFLYSKLSVD KSRWQRGDTF ICAVMHEALHNHYTQISLSH SPGK

The amino acid sequence of the CH3 domain of canine IgG.D is providedbelow:

(SEQ ID NO: 8) QPSVYV LPPSPKELSS SDTVTLTCLI KDFFPPEIDVEWQSNGQPEP ESKYHTTAPQ LDEDGSYFLYSKLSVDKSRW QQGDTFTCAV MHEALQNHYT DLSLSHSPGKFc Region of a Canine Fc region:

The Fc region of a canine IgG antibody comprises or consists of aminoacids 231 to 447 (according to EU numbering) of the canine IgG antibody.

The amino acid sequence of the Fc domain of canine IgG.A is providedbelow:

(SEQ ID NO: 9) VPEPLGGPSVLI FPPKPKDILR ITRTPEVTCV VLDLGREDPEVQISWFVDGK EVHTAKTQSR EQQFNGTYRV VSVLPIEHQDWLTGKEFKCR VNHIDLPSPI ERTISKARGR AHKPSVYVLPPSPKELSSSD TVSITCLIKD FYPPDIDVEW QSNGQQEPERKHRMTPPQLD EDGSYFLYSK LSVDKSRWQQ GDPFTCAVMH ETLQNHYTDL SLSHSPGK

The amino acid sequence of the Fc domain of canine IgG.B is providedbelow:

(SEQ ID NO: 10) APEMLGGPSVFIFPPK PKDTLLIART PEVTCVVVDLDPEDPEVQIS WFVDGKQMQT AKTQPREEQF NGTYRVVSVLPIGHQDWLKG KQFTCKVNNK ALPSPIERTI SKARGQAHQPSVYVLPPSRE ELSKNTVSLT CLIKDFFPPD IDVEWQSNGQQEPESKYRTT PPQLDEDGSY FLYSKLSVDK SRWQRGDTFI CAVMHEALHN HYTQESLSHS PGK

The amino acid sequence of the Fc domain of canine IgG.C is providedbelow:

(SEQ ID NO: 11) GCGLLGGPSVFIFPP KPKDILVTAR TPTVTCVVVDLDPENPEVQI SWFVDSKQVQ TANTQPREEQSNGTYRVVSV LPIGHQDWLS GKQFKCKVNN KALPSPIEEIISKTPGQAHQ PNVYVLPPSR DEMSKNTVTL TCLVKDFFPPEIDVEWQSNG QQEPESKYRM TPPQLDEDGS YFLYSKLSVDKSRWQRGDTF ICAVMHEALH NHYTQISLSH SPGK

The amino acid sequence of the Fc domain of canine IgG.D is providedbelow:

(SEQ ID NO: 12) VPESLGGPSV FIFPPKPKDI LRITRTPEIT CVVLDLGREDPEVQISWFVD GKEVHTAKTQ PREQQFNSTY RVVSVLPIEHQDWLTGKEFK CRVNHIGLPS PIERTISKAR GQAHQPSVYVLPPSPKELSS SDTVTLTCLI KDFFPPEIDV EWQSNGQPEPESKYHTTAPQ LDEDGSYFLY SKLSVDKSRW QQGDTFTCAV MHEALQNHYT DLSLSHSPGKSubstitutions in Canine IgG Fc that Improve Half-Life

Increased serum persistence is a beneficial property for therapeuticpolypeptides. This disclosure features substitutions in wild type canineIgG.A, IgG.B, IgG.C, and IgG.D Fc regions that enhance the half-life ofa polypeptide or polypeptides comprising these Fc regions in a dogrelative to a control polypeptide or control polypeptides, wherein thecontrol polypeptide or control polypeptides are identical to thepolypeptide or polypeptides except for having the corresponding wildtype canine IgG Fc region in place of the IgG Fc region variant. Thesubstitutions to increase half-life may be made in a canine CH2 region,a canine CH3 region, or in the context of a canine Fc (i.e., a CH2+CH3)region.

In some instances, this disclosure provides a canine IgG CH2 regionvariant comprising an amino acid sequence that is at least 75%, at least80%, at least 85%, at least 90%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% identical to the amino acidsequence set forth in any one of SEQ ID NOs.:1 to 4. Also provided arecanine IgG CH2 region variants comprising an amino acid sequence thatvaries from any one of SEQ ID NOs.:1 to 4 by 1 to 15 amino acids.

In other instances, this disclosure features a canine IgG CH3 regionvariant comprising an amino acid sequence that is at least 75%, at least80%, at least 85%, at least 90%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% identical to the amino acidsequence set forth in any one of SEQ ID NOs.:5 to 8. Also featured arecanine IgG CH3 region variants comprising an amino acid sequence thatvaries from any one of SEQ ID NOs.:5 to 8 by 1 to 15 amino acids.

In certain instances, this disclosure features a canine IgG Fc regionvariant comprising an amino acid sequence that is at least 75%, at least80%, at least 85%, at least 90%, at least 95%, at least 96%, at least97%, at least 98%, at least 99%, or 100% identical to the amino acidsequence set forth in any one of SEQ ID NOs.:9 to 12. Also disclosed arecanine IgG Fc region variants comprising an amino acid sequence thatvaries from any one of SEQ ID NOs.:9 to 12 by 1 to 20 amino acids.

In some instances, at least one (e.g. 1, 2, or 3) of the followingregions in the canine IgG Fc CH2 region variant are identical to thecorresponding regions in a wild type canine IgG Fc CH2 region:

-   -   amino acid positions 250-256;    -   amino acid positions 285-288; and    -   amino acid positions 307-315, wherein the amino acid positions        are based on EU numbering. In some instances, all of the above        regions in the canine IgG Fc CH2 region variant are identical to        the corresponding regions in a wild type canine IgG Fc CH2        region.

In some instances, at least one (e.g. 1 or 2) of the following regionsin the canine IgG Fc CH3 region variant are identical to thecorresponding regions in a wild type canine IgG Fc CH3 region:

-   -   Amino acid positions 376-380; and    -   Amino acid positions 428-436, wherein the amino acid positions        are based on EU numbering. In some instances, all of the above        regions in the canine IgG Fc CH3 region variant are identical to        the corresponding regions in a wild type canine IgG Fc CH3        region.

In some instances, at least one (e.g., 1, 2, 3, 4, or 5) of thefollowing regions in the canine IgG Fc variant are identical to thecorresponding regions in a wild type canine IgG Fc:

-   -   amino acid positions 250-256;    -   amino acid positions 285-288;    -   amino acid positions 307-315;    -   amino acid positions 376-380; and    -   amino acid positions 428-436, wherein the amino acid positions        are based on EU numbering. In some instances, all of the        following regions in the canine IgG Fc variant are identical to        the corresponding regions in a wild type canine IgG Fc.

In yet other embodiments, provided are a polypeptide or polypeptidescomprising a canine IgG Fc CH2 region variant, the CH2 region variantcomprising an amino acid sequence that is at least 75%, at least 80%, atleast 85%, at least 90%, at least 95%, at least 96%, at least 97%, atleast 98%, at least 99%, or 100% identical to the amino acid sequenceset forth in any one of SEQ ID NOs.:1 to 4.

In some embodiments, featured are a polypeptide or polypeptidescomprising a canine IgG Fc CH3 region variant, the CH3 region variantcomprising an amino acid sequence that is at least 75%, at least 80%, atleast 85%, at least 90%, at least 95%, at least 96%, at least 97%, atleast 98%, at least 99%, or 100% identical to the amino acid sequenceset forth in any one of SEQ ID NOs.:5 to 8.

In some embodiments, featured are a polypeptide or polypeptidescomprising a canine IgG Fc region variant, the Fc region variantcomprising an amino acid sequence that is at least 75%, at least 80%, atleast 85%, at least 90%, at least 95%, at least 96%, at least 97%, atleast 98%, at least 99%, or 100% identical to the amino acid sequenceset forth in any one of SEQ ID NOs.:9 to 12.

In some instances, the above-described polypeptide or polypeptidescomprise(s) a canine IgG CH2 region including one or more (e.g., 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) of:

-   -   an amino acid other than the wild type amino acid occurring at        amino acid position 250,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 251,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 252,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 254,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 256,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 285,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 286,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 307,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 308,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 309,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 311, or    -   an amino acid other than the wild type amino acid occurring at        amino acid position 315, wherein the amino acid positions are        based on EU numbering of the canine IgG.A, IgG.B, IgG.C, and        IgG.D antibodies.

In some embodiments, the above-described polypeptide or polypeptidescomprise(s) a canine IgG CH3 region including one or more (e.g., 1, 2,3, 4, 5, 6, 7, or 8) of:

-   -   an amino acid other than the wild type amino acid occurring at        amino acid position 378,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 380,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 428,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 430,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 433,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 434,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 435, or    -   an amino acid other than the wild type amino acid occurring at        amino acid position 436, wherein the amino acid positions are        based on EU numbering of the canine IgG.A, IgG.B, IgG.C, and        IgG.D antibodies.

In certain embodiments, the above-described polypeptide or polypeptidescomprise a canine IgG Fc region including one or more (e.g., 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) of:

-   -   an amino acid other than the wild type amino acid occurring at        amino acid position 250,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 251,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 252,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 254,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 256,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 285,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 286,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 307,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 308,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 309,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 311,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 315,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 378,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 380,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 428,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 430,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 433,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 434,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 435,    -   an amino acid other than the wild type amino acid occurring at        amino acid position 436, wherein the amino acid positions are        based on EU numbering of the canine IgG.A, IgG.B, IgG.C, and        IgG.D antibodies.

The substitutions that are encompassed by the present disclosure includeone or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,16, 17, 18, 19, or 20) of those disclosed in Table 1.

TABLE 1 Position (EU Canine Canine Canine Canine Substi- Numbering)hIgG1 IgG.A IgG.B IgG.C IgG.D tution CH2 Region 250 T I T I I E or Q 251L L L L L D or E 252 M R L V R Y 254 S T A A T T 256 T T T T T D, E, orF 285 H H Q Q H N or D 286 N T T T T D 307 T P P P P R, Q, or A 308 V II I I P 309 L E G G E P 311 Q Q Q Q Q V 315 N T K S T D CH3 Region 378 AD D D D V 380 E E E E E A 428 M M M M M L 430 E E E E E A or K 433 H Q HH Q K 434 N N N N N S, A, or F 435 H H H H H Y 436 Y Y Y Y Y H

In some instances, the substitutions that are encompassed by the presentdisclosure include one or more (e.g., 1, 2, 3, or 4) of those disclosedin Table 2.

TABLE 2 Position (EU Canine Canine Canine Canine Substi- Numbering)hIgG1 IgG.A IgG.B IgG.C IgG.D tution CH2 Region 252 M R L V R Y or M 254S T A A T T 256 T T T T T E CH3 Region 434 N N N N N Y, W, R, or H

All possible combinations and permutations of the substitutionsdisclosed above are encompassed by this disclosure. In some instances,the substitutions include one or more of the following substitutions:

-   -   (i) Tyr at amino acid position 252, Thr at amino acid position        254, and Glu at amino acid position 256;    -   (ii) Leu at amino acid position 428 and Ser at amino acid        position 434;    -   (iii) Asp at amino acid position 256, Arg at amino acid position        307, and Val at amino acid position 311;    -   (iv) Asp at amino acid position 256, Asp at amino acid position        315, and Val at amino acid position 378;    -   (v) Asp at amino acid position 256, Asp at amino acid position        286, Arg at amino acid position 307, and Val at amino acid        position 311;    -   (vi) Asn at amino acid position 285, Gln at amino acid position        307, and Asp at amino acid position 315;    -   (vii) Asp at amino acid position 256, Arg at amino acid position        307, Val at amino acid position 311, and Val at amino acid        position 378;    -   (viii) Asp at amino acid position 285, Val at amino acid        position 311, and Val at amino acid position 378;    -   (ix) Asp at amino acid position 256, Asp at amino acid position        285, and Val at amino acid position 378;    -   (x) Asp at amino acid position 256, Val at amino acid position        311, and Val at amino acid position 378;    -   (xi) Asp at amino acid position 256, Asp at amino acid position        285, Asp at amino acid position 286, Arg at amino acid position        307, and Val at amino acid position 378;    -   (xii) Asp at amino acid position 256, Asp at amino acid position        286, Arg at amino acid position 307, Val at amino acid position        311, and Val at position 378;    -   (xiii) Gln at amino acid position 307, Val at amino acid        position 311, and Val at amino acid position 378;    -   (xiv) Asp at amino acid position 285, Gln at amino acid position        307, and Val at amino acid position 378;    -   (xv) Asp at amino acid position 256, Asp at amino acid position        285, Arg at amino acid position 307, Val at amino acid position        311, and Val at amino acid position 378;    -   (xvi) Gln at amino acid position 307, Ala at amino acid position        380, Ser or Ala at amino acid position 434;    -   (xvii) Leu at amino acid position 428, and Ser or Ala at amino        acid position 434;    -   (xviii) Gln at amino acid position 250 and Leu at amino acid        position 428;    -   (xix) Glu at amino acid position 250 and Glu at amino acid        position 251;    -   (xx) Phe at amino acid position 256 and Phe at amino acid        position 309;    -   (xxi) Ala at amino acid position 430 and Lys at amino acid        position 433;    -   (xxii) Phe at amino acid position 434 and His at amino acid        position 436;    -   (xxiii) Tyr at amino acid position 435 and His at amino acid        position 436;

In some instances, the substitutions do not include the combination ofTyr at amino acid position 252, Thr at amino acid position 254, and Gluat amino acid position 256.

The substitutions may be made on one or both chains of a CH2 domain, aCH3 domain, or an Fc domain. In some instances, the substitutions onboth chains of a CH2 domain, a CH3 domain, or an Fc domain areidentical. In some instances, the substitutions on both chains of a CH2domain, a CH3 domain, or an Fc domain are not identical. In someinstances, the Fc region includes one or more additional substitutionsthat increase or decrease effector function, improve productheterogeneity.

Other Substitutions that Can be Combined with the Half-Life EnhancingSubstitutions

The development of a therapeutic polypeptide/protein (e.g., a monoclonalantibody) is a complex process that entails coordination of a complexset of activities to generate the desired polypeptide/protein. Theseinclude optimization of the specificity, affinity, functional activity,expression level in engineered cell lines, long-term stability,elimination or enhancement of effector functions and development ofcommercially viable manufacturing and purification methods. Thisdisclosure encompasses any additional substitution that facilitates anyone or more of the above goals.

In some embodiments, the substitutions are introduced to reduce effectorfunction of the canine Fc region. Such substitutions may be at one ormore (e.g., 1, 2, 3, 4, 5, 6, or 7) of the following positions of thecanine IgG (numbering according to EU numbering): 238, 265, 297, 298,299, 327, and 329. The substitution(s) can be to any of the other 19amino acids. In some instances, the substitution is conservative. Incertain non-limiting instances, the substituted amino acid at position238 is Ala; the substituted amino acid at position 265 is Ala; thesubstituted amino acid at position 297 is Ala or Gln; the substitutedamino acid at position 298 is Pro; the substituted amino acid atposition 299 is Ala; the substituted amino acid at position 327 is Gly;and the substituted amino acid at position 329 is Ala. In someinstances, the variant Fc region is from a canine IgG.B or IgG.Cantibody.

In some embodiments, substitutions are introduced to a wild type canineIgG Fc region to enhance binding to Protein A so as to facilitatepurification by protein A chromatography. Such substitutions may be atone or both (e.g., 1, 2, 3, 4, 5, 6, or 7) of the following positions ofthe canine IgG (numbering according to EU numbering): 252 and 254. Thesubstitution(s) can be to any of the other 19 amino acids. In someinstances, the substitution is conservative. In certain non-limitinginstances, the substituted amino acid at position 252 is Met; and thesubstituted amino acid at position 254 is Ser.

In some embodiments, the substitutions are made to alter bindingaffinity to FcRn as compared to a parent polypeptide or a wildtypepolypeptide (e.g., to increase or reduce binding affinity with FcRn). Insome variations, the modification can be one, two, three, or fourmodifications that are selected from the group consisting of: 308F,428L, 434M and 434S, where the numbering is according to the EUnumbering. In some embodiments, the Fc variant includes one or moremodifications selected from the group consisting of: 252Y/428L,428L/434H, 428L/434F, 428L/434Y, 428L/434A, 428L/434M, and 428L/4345,where the numbering is according to the EU numbering. In someembodiments, the Fc variant includes one or more modification selectedfrom the group consisting of: 428L/4345, 308F/428L/4345, where thenumbering is according to the EU numbering. In some embodiments, the Fcvariant includes one or more modifications selected from the groupconsisting of: 25911434S, 308F/434S, 308F/428L/4345, 2591/308F/4345,307Q/308F/434S, 2501/308F/4345, and 308F/319L/4345, where the numberingis according to the EU numbering. A detailed description of thesemodifications is described in e.g., U.S. Pat. No. 8,883,973B2, which isincorporated herein by reference in its entirety.

In some embodiments, the polypeptide comprises a hinge region of acanine antibody. In some embodiments, modifications can be made to thehinge region of the canine antibody to increase half-life. In someembodiments, the modification is 228P according to EU numbering.

In some embodiments, the binding with FcRn is pH-dependent. H310 andH435 (EU numbering) can be critical for pH-dependent binding. Thus, insome embodiments, the amino acids at position 310 (EU numbering) ishistidine. In some embodiments, the amino acids at position 435 (EUnumbering) is histidine. In some embodiments, the amino acids at bothpositions are histidine.

In some embodiments, the Fc region has LALA mutations (L234A and L235Amutations in EU numbering), or LALA-PG mutations (L234A, L235A, P329Gmutations in EU numbering). In some embodiments, the amino acid residueat position 234 (EU numbering) is Ala. In some embodiments, the aminoacid residue at position 234 (EU numbering) is Ala. In some embodiments,the amino acid residues at positions 234 and 235 (EU numbering) are Ala.

Polypeptides Comprising the Canine IgG Fc Variants

The disclosure encompasses any polypeptide that may benefit from havingan increased half-life in a dog. To increase half-life thesepolypeptides are designed to include an Fc region variant (e.g., a CH2region, a CH3 region, a CH2+CH3 region) disclosed above.

Exemplary polypeptides include, but are not limited to, wholeantibodies, scFvs, nanobodies, ligand-binding portions of a receptor,cytokines, growth factors, enzymes, and peptides. For example a CH3domain variant disclosed above may be attached to an scFv nanobody,ligand-binding portion of a receptor (e.g., the ligand-binding portionof canine IL-13Ra1 or IL-13Ra2), a cytokine, a growth factor, an enzyme,or a peptide. Alternatively, an Fc region variant disclosed above may beattached to these polypeptides. In another embodiment, a canine orcaninized antibody is modified to include an Fc region variant disclosedherein.

In certain embodiments, the polypeptides of this disclosure include anantibody hinge region. The hinge region may be placed between theantigen or ligand-binding domain of the polypeptide and the Fc regionvariant. In some instances, the hinge region is attached to theC-terminus of a cytokine, a growth factor, an enzyme, or a peptide andthe hinge region is attached to the N-terminus of the Fc region variant.Exemplary hinge region sequences are provided below.

IgG.A: (SEQ ID NO: 17) FNECRCTDTPPCPVPEP; IgG.B: (SEQ ID NO: 18)PKRENGRVPRPPDCPKCPAPEM; IgG.C: (SEQ ID NO: 19) AKECECKCNCNNCPCPGCGL;IgG.D: (SEQ ID NO: 20) PKESTCKCISPCPVPES; and IgG.Dmut: (SEQ ID NO: 21)PKESTCKCIPPCPVPES.

The hinge region, if used, in a recombinant protein of this disclosuremay include zero to six (i.e., 0, 1, 2, 3, 4, 5, or 6) amino acidsubstitutions relative to an amino acid sequence set forth in any one ofSEQ ID NOs.:17-21. In some instances, the hinge region used in arecombinant protein of this disclosure is at least 80%, at least 85%, atleast 90%, at least 95%, at least 96%, at least 97%, at least 98%, atleast 99%, or 100% identical to an amino acid sequence set forth in anyone of SEQ ID NOs.:17-21.

In certain embodiments, a linker sequence may be used instead of anantibody hinge sequence to connect the polypeptide (e.g., antibodies,ligand-binding domains of receptors, enzymes, ligands, peptides) to thecanine Fc region variants disclosed herein. In certain embodiments, thelinker is made up of from 1 to 20 amino acids linked by peptide bonds,wherein the amino acids are selected from the 20 naturally occurringamino acids. Some of these amino acids may be glycosylated, as is wellunderstood by those in the art. In other embodiments, the 1 to 20 aminoacids are selected from glycine, alanine, proline, asparagine,glutamine, and lysine. In other embodiments, a linker is made up of amajority of amino acids that are sterically unhindered, such as glycineand alanine. Examples of peptide linkers include: Gly, Ser; Gly Ser; GlyGly Ser; Ser Gly Gly; Gly Gly Gly Ser (SEQ ID NO:22); Ser Gly Gly Gly(SEQ ID NO:23); Gly Gly Gly Gly Ser (SEQ ID NO:24); Ser Gly Gly Gly Gly(SEQ ID NO:25); Gly Gly Gly Gly Gly Ser (SEQ ID NO:26); Ser Gly Gly GlyGly Gly (SEQ ID NO:27); Gly Gly Gly Gly Gly Gly Ser (SEQ ID NO:28); SerGly Gly Gly Gly Gly Gly (SEQ ID NO:29); (Gly Gly Gly Gly Ser). (SEQ IDNO:24)_(n), wherein n is an integer of one or more (e.g., 1, 2, 3, 4,5); and (Ser Gly Gly Gly Gly)_(n)(SEQ ID NO:25)_(n), wherein n is aninteger of one or more (e.g., 1, 2, 3, 4, 5).

Non-peptide linkers may also be used to link the polypeptide orpolypeptides of interest to an Fc region variant disclosed herein. Forexample, alkyl linkers such as —NH(CH₂)_(n)C(O)—, wherein n=2-20 can beused. These alkyl linkers may further be substituted by anynon-sterically hindering group such as lower alkyl (e.g., C₁-C₆) loweracyl, halogen (e.g., Cl, Br), CN, NH₂, phenyl, etc.

The polypeptide or polypeptides of this disclosure may comprise abinding domain. The binding domain can specifically bind to a protein,subunit, domain, motif, and/or epitope of a selected target describedherein. In some embodiments, the polypeptide or polypeptides (e.g.,fusion polypeptide) can comprise a protein, wherein the protein is atherapeutic protein described herein. In some embodiments, the target(e.g., for the target of the binding domain) or the therapeutic protein(e.g., for the fusion polypeptide) is selected from the group consistingof: 17-IA, 4-1BB, 4Dc, 6-keto-PGF1a, 8-iso-PGF2a, 8-oxo-dG, Al AdenosineReceptor, A33, ACE, ACE-2, Activin, Activin A, Activin AB, Activin B,Activin C, Activin RIA, Activin RIA ALK-2, Activin RIB ALK-4, ActivinRIIA, Activin RIIB, ADAM, ADAM10, ADAM12, ADAM15, ADAM17/TACE, ADAMS,ADAMS, ADAMTS, ADAMTS4, ADAMTS5, Addressins, aFGF, ALCAM, ALK, ALK-1,ALK-7, alpha-1-antitrypsin, alpha-V/beta-1 antagonist, ANG, Ang, APAF-1,APE, APJ, APP, APRIL, AR, IgE, Angiotensin type 1 (AT1) receptor,Angiotensin type 2 (AT2) receptor, ARC, ART, Artemin, anti-Id, ASPARTIC,Atrial natriuretic factor, av/b3 integrin, Axl, b2M, B7-1, B7-2, B7-H,B-lymphocyte Stimulator (BlyS), BACE, BACE-1, Bad, BAFF, BAFF-R, Bag-1,BAK, Bax, BCA-1, BCAM, Bcl, BCMA, BDNF, b-ECGF, bFGF, BID, Bik, BIM,BLC, BL-CAM, BLK, BMP, BMP-2 BMP-2a, BMP-3 Osteogenin, BMP-4 BMP-2b,BMP-5, BMP-6 Vgr-1, BMP-7 (OP-1), BMP-8 (BMP-8a, OP-2), BMPR, BMPR-IA(ALK-3), BMPR-IB (ALK-6), BRK-2, RPK-1, BMPR-II (BRK-3), BMPs, b-NGF,BOK, Bombesin, Bone-derived neurotrophic factor, BPDE, BPDE-DNA, BTC,complement factor 3 (C3), C3a, C4, C5, C5a, C10, CA125, CAD-8,Calcitonin, cAMP, carcinoembryonic antigen (CEA), carcinoma-associatedantigen, Cathepsin A, Cathepsin B, Cathepsin C/DPPI, Cathepsin D,Cathepsin E, Cathepsin H, Cathepsin L, Cathepsin 0, Cathepsin S,Cathepsin V, Cathepsin X/Z/P, CBL, CC1, CCK2, CCL, CCL1, CCL11, CCL12,CCL13, CCL14, CCL15, CCL16, CCL17, CCL18, CCL19, CCL2, CCL20, CCL21,CCL22, CCL23, CCL24, CCL25, CCL26, CCL27, CCL28, CCL3, CCL4, CCL5, CCL6,CCL7, CCL8, CCL9/10, CCR, CCR1, CCR10, CCR10, CCR2, CCR3, CCR4, CCR5,CCR6, CCR7, CCR8, CCR9, CD1, CD2, CD3, CD3E, CD4, CD5, CD6, CD7, CD8,CD10, CD11a, CD11b, CD11c, CD13, CD14, CD15, CD16, CD18, CD19, CD20,CD21, CD22, CD23, CD25, CD27L, CD28, CD29, CD30, CD30L, CD32, CD33 (p67proteins), CD34, CD38, CD40, CD40L, CD44, CD45, CD46, CD47, CD49a, CD52,CD54, CD55, CD56, CD61, CD64, CD66e, CD74, CD80 (B7-1), CD89, CD95,CD123, CD137, CD138, CD140a, CD146, CD147, CD148, CD152, CD164, CEACAM5,CFTR, cGMP, CINC, Clostridium botulinum toxin, Clostridium perfringenstoxin, CKb8-1, CLC, CMV, CMV UL, CNTF, CNTN-1, COX, C-Ret, CRG-2, CT-1,CTACK, CTGF, CTLA-4, CX3CL1, CX3CR1, CXCL, CXCL1, CXCL2, CXCL3, CXCL4,CXCL5, CXCL6, CXCL7, CXCL8, CXCL9, CXCL10, CXCL11, CXCL12, CXCL13,CXCL14, CXCL15, CXCL16, CXCR, CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6,cytokeratin tumor-associated antigen, DAN, DCC, DcR3, DC-SIGN, Decayaccelerating factor, des(1-3)-IGF-I (brain IGF-1), Dhh, digoxin, DNAM-1,Dnase, Dpp, DPPIV/CD26, Dtk, EGAD, EDA, EDA-A1, EDA-A2, EDAR, EGF, EGFR(ErbB-1), EMA, EMMPRIN, ENA, endothelin receptor, Enkephalinase, eNOS,Eot, eotaxinl, EpCAM, Ephrin B2/EphB4, EPO, ERCC, E-selectin, ET-1,Factor IIa, Factor VII, Factor VIIIc, Factor IX, fibroblast activationprotein (FAP), Fas, FcR1, FEN-1, Ferritin, FGF, FGF-19, FGF-2, FGF3,FGF-8, FGFR, FGFR-3, Fibrin, FL, FLIP, Flt-3, Flt-4, Folliclestimulating hormone, Fractalkine, FZD1, FZD2, FZD3, FZD4, FZD5, FZD6,FZD7, FZD8, FZD9, FZD10, G250, Gas 6, GCP-2, GCSF, GD2, GD3, GDF, GDF-1,GDF-3 (Vgr-2), GDF-5 (BMP-14, CDMP-1), GDF-6 (BMP-13, CDMP-2), GDF-7(BMP-12, CDMP-3), GDF-8 (Myostatin), GDF-9, GDF-15 (MIC-1), GDNF, GDNF,GFAP, GFRa-1, GFR-alpha1, GFR-alpha2, GFR-alpha3, GITR, GLP1, GLP2,Glucagon, Glut 4, glycoprotein IIb/IIIa (GP IIb/IIIa), GM-CSF, gp130,gp72, GRO, GnRH, Growth hormone releasing factor, Hapten (NP-cap orNIP-cap), HB-EGF, HCC, HCMV gB envelope glycoprotein, HCMV) gH envelopeglycoprotein, HCMV UL, Hemopoietic growth factor (HGF), Hep B gp120,heparanase, Her2, Her2/neu (ErbB-2), Her3 (ErbB-3), Her4 (ErbB-4),herpes simplex virus (HSV) gB glycoprotein, HSV gD glycoprotein, HGFA,High molecular weight melanoma-associated antigen (HMW-MAA), HIV gp120,HIV IIIB gp120 V3 loop, HLA, HLA-DR, HM1.24, HMFG PEM, HRG, Hrk, cardiacmyosin, cytomegalovirus (CMV), growth hormone (GH), HVEM, 1-309, IAP,ICAM, ICAM-1, ICAM-3, ICE, ICOS, IFNg, Ig, IgA receptor, IgE, IGF, IGFbinding proteins, IGF-1R, IGFBP, IGF-I, IGF-II, IL, IL-1, IL-1R, IL-2,IL-2R, IL-4, IL-4R, IL-5, IL-5R, IL-6, IL-6R, IL-8, IL-9, IL-10, IL-12,IL-13, IL-15, IL-17, IL-18, IL-18R, IL-21, IL-22, IL-23, IL-25, IL-31,IL-33, interleukin receptor (e.g., IL-1R, IL-2R, IL-4R, IL-5R, IL-6R,IL-8R, IL-9R, IL-10R, IL-12R, IL-13R, IL-15R, IL-17R, IL-18R, IL-21R,IL-22R, IL-23R, IL-25R, IL-31R, IL-33R), interferon (INF)-alpha,INF-beta, INF-gamma, Inhibin, iNOS, Insulin A-chain, Insulin B-chain,Insulin-like growth factor 1, integrin alpha2, integrin alpha3, integrinalpha4, integrin alpha4/beta1, integrin alpha4/beta7, integrin alpha5(alphaV), integrin alpha5/beta1, integrin alpha5/beta3, integrin alpha6,integrin beta1, integrin beta2, interferon gamma, IP-10, I-TAC, JE,Kallikrein 2, Kallikrein 5, Kallikrein 6, Kallikrein 11, Kallikrein 12,Kallikrein 14, Kallikrein 15, Kallikrein L1, Kallikrein L2, KallikreinL3, Kallikrein L4, KC, KDR, Keratinocyte Growth Factor (KGF), laminin 5,LAMP, LAP, LAP (TGF-1), Latent TGF-1, Latent TGF-1 bpl, LBP, LDGF,LECT2, Lefty, Lewis-Y antigen, Lewis-Y related antigen, LFA-1, LFA-3,Lfo, LIF, LIGHT, lipoproteins, LIX, LKN, Lptn, L-Selectin, LT-a, LT-b,LTB4, LTBP-1, Lung surfactant, Luteinizing hormone, Lymphotoxin BetaReceptor, Mac-1, MAdCAM, MAG, MAP2, MARC, MCAM, MCAM, MCK-2, MCP, M-CSF,MDC, Mer, METALLOPROTEASES, MGDF receptor, MGMT, MHC(HLA-DR), MIF, MIG,MIP, MIP-1-alpha, MK, MMAC1, MMP, MMP-1, MMP-10, MMP-11, MMP-12, MMP-13,MMP-14, MMP-15, MMP-2, MMP-24, MMP-3, MMP-7, MMP-8, MMP-9, MPIF, Mpo,MSK, MSP, mucin (Mucl), MUC18, Muellerian-inhibitin substance, Mug,MuSK, NAIP, NAP, NAV 1.7, NCAD, N-Cadherin, NCA 90, NCAM, NCAM,Neprilysin, Neurotrophin-3, −4, or −6, Neurturin, Neuronal growth factor(NGF), NGFR, NGF-beta, nNOS, NO, NOS, Npn, NRG-3, NT, NTN, OB, OGG1,OPG, OPN, OSM, OX40L, OX40R, p150, p95, PADPr, Parathyroid hormone,PARC, PARP, PBR, PBSF, PCAD, P-Cadherin, PCNA, PD1, PDL1, PDGF, PDGF,PDK-1, PECAM, PEM, PF4, PGE, PGF, PGI2, PGD2, PIN, PLA2, placentalalkaline phosphatase (PLAP), P1GF, PLP, PP14, Proinsulin, Prorelaxin,Protein C, PS, PSA, PSCA, prostate specific membrane antigen (PSMA),PTEN, PTHrp, Ptk, PTN, R51, RANK, RANKL, RANTES, RANTES, RelaxinA-chain, Relaxin B-chain, renin, respiratory syncytial virus (RSV) F,RSV Fgp, Ret, Rheumatoid factors, RLIP76, RPA2, RSK, S100, SCF/KL,SDF-1, SERINE, Serum albumin, sFRP-3, Shh, SIGIRR, SK-1, SLAM, SLPI,SMAC, SMDF, SMOH, SOD, SPARC, Stat, STEAP, STEAP-II, TACE, TACI, TAG-72(tumor-associated glycoprotein-72), TARC, TCA-3, T-cell receptors (e.g.,T-cell receptor alpha/beta), TdT, TECK, TEM1, TEMS, TEM7, TEM8, TERT,testicular PLAP-like alkaline phosphatase, TfR, TGF, TGF-alpha,TGF-beta, TGF-beta Pan Specific, TGF-beta R1 (ALK-5), TGF-beta R11,TGF-beta RIIb, TGF-beta RIII, TGF-beta1, TGF-beta2, TGF-beta3,TGF-beta4, TGF-beta5, Thrombin, Thymus Ck-1, Thyroid stimulatinghormone, Tie, TIMP, TIQ, Tissue Factor, TMEFF2, Tmpo, TMPRSS2, TNF,TNF-alpha, TNF-alpha beta, TNF-beta2, TNFc, TNF-RI, TNF-RII, TNFRSF10A(TRAIL R1Apo-2, DR4), TNFRSF10B (TRAIL R2DR5, KILLER, TRICK-2A,TRICK-B), TNFRSF10C (TRAIL R3DcR1, LIT, TRID), TNFRSF10D (TRAIL R4 DcR2,TRUNDD), TNFRSF11A (RANK ODF R, TRANCE R), TNFRSF11B (OPG OCIF, TR1),TNFRSF12 (TWEAK R FN14), TNFRSF13B (TACI), TNFRSF13C (BAFF R), TNFRSF14(HVEM ATAR, HveA, LIGHT R, TR2), TNFRSF16 (NGFR p75NTR), TNFRSF17(BCMA), TNFRSF18 (GITR AITR), TNFRSF19 (TROY TAJ, TRADE), TNFRSF19L(RELT), TNFRSF1A (TNF R1CD120a, p55-60), TNFRSF1B (TNF RII CD120b,p′75-80), TNFRSF26 (TNFRH3), TNFRSF3 (LTbR TNF RIII, TNFC R), TNFRSF4(0X40 ACT35, TXGP1 R), TNFRSF5 (CD40 p50), TNFRSF6 (Fas Apo-1, APT1,CD95), TNFRSF6B (DcR3M68, TR6), TNFRSF7 (CD27), TNFRSF8 (CD30), TNFRSF9(4-1BB CD137, ILA), TNFRSF21 (DR6), TNFRSF22 (DCTRAIL R2 TNFRH2),TNFRST23 (DCTRAIL R1TNFRH1), TNFRSF25 (DR3Apo-3, LARD, TR-3, TRAMP,WSL-1), TNFSF10 (TRAIL Apo-2 Ligand, TL2), TNFSF11 (TRANCE/RANK LigandODF, OPG Ligand), TNFSF12 (TWEAK Apo-3 Ligand, DR3Ligand), TNFSF13(APRIL TALL2), TNFSF13B (BAFF BLYS, TALL1, THANK, TNFSF20), TNFSF14(LIGHT HVEM Ligand, LTg), TNFSF15 (TL1A/VEGI), TNFSF18 (GITR Ligand AITRLigand, TL6), TNFSF1A (TNF-α Conectin, DIF, TNFSF2), TNFSF1B (TNF-b LTa,TNFSF1), TNFSF3 (LTb TNFC, p33), TNFSF4 (0X40 Ligand gp34, TXGP1),TNFSF5 (CD40 Ligand CD154, gp39, HIGM1, IMD3, TRAP), TNFSF6 (Fas LigandApo-1 Ligand, APT1 Ligand), TNFSF7 (CD27 Ligand CD70), TNFSF8 (CD30Ligand CD153), TNFSF9 (4-1BB Ligand CD137 Ligand), TP-1, t-PA, Tpo,TRAIL, TRAIL R, TRAIL-R1, TRAIL-R2, TRANCE, transferring receptor, TRF,Trk (e.g., TrkA), TROP-2, TSG, TSLP, tumor-associated antigen CA 125,tumor-associated antigen expressing Lewis Y related carbohydrate, TWEAK,TXB2, Ung, UPAR, uPAR-1, Urokinase, VCAM, VCAM-1, VECAD, VE-Cadherin,VE-cadherin-2, VEFGR-1 (fit-1), VEGF, VEGFR, VEGFR-3 (flt-4), VEGI, VIM,Viral antigens, VLA, VLA-1, VLA-4, VNR integrin, von Willebrands factor,WIF-1, WNT1, WNT2, WNT2B/13, WNT3, WNT3A, WNT4, WNT5A, WNT5B, WNT6,WNT7A, WNT7B, WNT8A, WNT8B, WNT9A, WNT9A, WNT9B, WNT10A, WNT10B, WNT11,WNT16, XCL1, XCL2, XCR1, XCR1, XEDAR, XIAP, XPD, and receptors forhormones and growth factor.

In some embodiments, the binding domain specifically binds to one ormore therapeutic targets or antigens in canine, such as, but are notlimited to, ACE, ACE-2, Activin, Activin A, Activin AB, Activin B,Activin C, Activin RIA, Activin RIA ALK-2, Activin RIB ALK-4, ActivinRIIA, Activin RIIB, ADAM, ADAM10, ADAM12, ADAM15, ADAM17/TACE, ADAMS,ADAMS, ADAMTS, ADAMTS4, ADAMTS5, ANG, Ang, Angiotensin type 1 (AT1)receptor, Angiotensin type 2 (AT2) receptor, Atrial natriuretic factor,av/b3 integrin, b-ECGF, CD19, CD20, CD30, CD34, CD40, CD40L, CD47, COX,CTLA-4, EGFR (ErbB-1), EPO, Follicle stimulating hormone, GDF-8(Myostatin), GLP1, GLP2, GnRH, Growth hormone releasing factor, IgE, IL,IL-1, IL-1R, IL-2, IL-2R, IL-4, IL-4R, IL-5, IL-5R, IL-6, IL-6R, IL-8,IL-9, IL-10, IL-12, IL-13, IL-15, IL-17, IL-18, IL-18R, IL-21, IL-22,IL-23, IL-25, IL-31, IL-33, interleukin receptor (e.g., IL-1R, IL-2R,IL-4R, IL-5R, IL-6R, IL-8R, IL-9R, IL-10R, IL-12R, IL-13R, IL-15R,IL-17R, IL-18R, IL-21R, IL-22R, IL-23R, IL-25R, IL-31R, IL-33R), LAP(TGF-1), Latent TGF-1, Latent TGF-1 bpl, LFA-1, Neuronal growth factor(NGF), NGFR, NGF-beta, OX40L, OX40R, PD1, PDL1, TGF, TGF-alpha,TGF-beta, TGF-beta Pan Specific, TGF-beta R1 (ALK-5), TGF-beta R11,TGF-beta RIIb, TGF-beta RIII, TGF-beta1, TGF-beta2, TGF-beta3,TGF-beta4, TGF-beta5, TNF, TNF-alpha, TNF-alpha beta, TNF-beta2, TNFc,TNF-RI, TNF-RII, TNFRSF16 (NGFR p75NTR), TNFRSF9 (4-1BB CD137, ILA),VEFGR-1 (fit-1), VEGF, VEGFR, and VEGFR-3 (flt-4).

In some embodiments, the polypeptide or polypeptides can comprise aprotein, wherein the protein is a therapeutic protein, e.g., EPO, CTLA4,LFA3, VEGFR1/VEGFR3, IL-1R, IL-4R, GLP-1 receptor agonist, orThrombopoietin binding peptide. In some embodiments, the therapeuticprotein is ACE, ACE-2, Activin, Activin A, Activin AB, Activin B,Activin C, Activin RIA, Activin RIA ALK-2, Activin RIB ALK-4, ActivinRIIA, Activin RIIB, ADAM, ADAM10, ADAM12, ADAM15, ADAM17/TACE, ADAMS,ADAMS, ADAMTS, ADAMTS4, ADAMTS5, ANG, Ang, Angiotensin type 1 (AT1)receptor, Angiotensin type 2 (AT2) receptor, Atrial natriuretic factor,av/b3 integrin, b-ECGF, CD19, CD20, CD30, CD34, CD40, CD40L, CD47, COX,CTLA-4, EGFR (ErbB-1), EPO, Follicle stimulating hormone, GDF-8(Myostatin), GLP1, GLP2, GnRH, Growth hormone releasing factor, IgE, IL,IL-1, IL-1R, IL-2, IL-2R, IL-4, IL-4R, IL-5, IL-5R, IL-6, IL-6R, IL-8,IL-9, IL-10, IL-12, IL-13, IL-15, IL-17, IL-18, IL-18R, IL-21, IL-22,IL-23, IL-25, IL-31, IL-33, interleukin receptor (e.g., IL-1R, IL-2R,IL-4R, IL-5R, IL-6R, IL-8R, IL-9R, IL-10R, IL-12R, IL-13R, IL-15R,IL-17R, IL-18R, IL-21R, IL-22R, IL-23R, IL-25R, IL-31R, IL-33R), LAP(TGF-1), Latent TGF-1, Latent TGF-1 bpl, LFA-1, Neuronal growth factor(NGF), NGFR, NGF-beta, OX40L, OX40R, PD1, PDL1, TGF, TGF-alpha,TGF-beta, TGF-beta Pan Specific, TGF-beta R1 (ALK-5), TGF-beta R11,TGF-beta TGF-beta RIII, TGF-beta1, TGF-beta2, TGF-beta3, TGF-beta4,TGF-beta5, TNF, TNF-alpha, TNF-alpha beta, TNF-beta2, TNFc, TNF-RI,TNF-RII, TNFRSF16 (NGFR p75NTR), TNFRSF9 (4-1BB CD137, ILA), VEFGR-1(fit-1), VEGF, VEGFR, or VEGFR-3 (flt-4).

In some embodiments, the therapeutic protein is any protein describedherein. In some embodiments, the polypeptide or polypeptides furthercomprises a canine IgG CH2 domain, IgG CH3 domain, or IgG Fc region asdescribed herein. The modified canine IgG CH2 domain, IgG CH3 domain, orIgG Fc region can enhance the half-life the therapeutic proteins invivo.

Pharmaceutical Compositions

To prepare pharmaceutical or sterile compositions of a polypeptide orpolypeptides described herein, the polypeptide or polypeptides can beadmixed with a pharmaceutically acceptable carrier or excipient. (See,e.g., Remington's Pharmaceutical Sciences and U.S. Pharmacopeia:National Formulary, Mack Publishing Company, Easton, Pa. (1984)).

Formulations of therapeutic and diagnostic agents may be prepared bymixing with acceptable carriers, excipients, or stabilizers in the formof, e.g., lyophilized powders, slurries, aqueous solutions orsuspensions (see, e.g., Hardman, et al. (2001) Goodman and Gilman's ThePharmacological Basis of Therapeutics, McGraw-Hill, New York, N.Y.;Gennaro (2000) Remington: The Science and Practice of Pharmacy,Lippincott, Williams, and Wilkins, New York, N.Y.; Avis, et al. (eds.)(1993) Pharmaceutical Dosage Forms: Parenteral Medications, MarcelDekker, NY; Lieberman, et al. (eds.) (1990) Pharmaceutical Dosage Forms:Tablets, Marcel Dekker, NY; Lieberman, et al. (eds.) (1990)Pharmaceutical Dosage Forms: Disperse Systems, Marcel Dekker, NY; Weinerand Kotkoskie (2000) Excipient Toxicity and Safety, Marcel Dekker, Inc.,New York, N.Y.). In one embodiment, the polypeptide or polypeptides ofthe present invention are diluted to an appropriate concentration in asodium acetate solution pH 5-6, and NaCl or sucrose is added fortonicity. Additional agents, such as polysorbate 20 or polysorbate 80,may be added to enhance stability.

Toxicity and therapeutic efficacy of the polypeptide compositions,administered alone or in combination with another agent, can bedetermined by standard pharmaceutical procedures in cell cultures orexperimental animals, e.g., for determining the LD₅₀ (the dose lethal to50% of the population) and the ED₅₀ (the dose therapeutically effectivein 50% of the population). The dose ratio between toxic and therapeuticeffects is the therapeutic index (LD₅₀/ED₅₀). In particular aspects, apolypeptide or polypeptides exhibiting high therapeutic indices aredesirable. The data obtained from these cell culture assays and animalstudies can be used in formulating a range of dosage for use in canines.The dosage of such compounds lies preferably within a range ofcirculating concentrations that include the ED₅₀ with little or notoxicity. The dosage may vary within this range depending upon thedosage form employed and the route of administration.

The mode of administration can vary. Suitable routes of administrationinclude oral, rectal, transmucosal, intestinal, parenteral;intramuscular, subcutaneous, intradermal, intramedullary, intrathecal,direct intraventricular, intravenous, intraperitoneal, intranasal,intraocular, inhalation, insufflation, topical, cutaneous, transdermal,or intra-arterial. In some embodiments, the polypeptide or polypeptidescan be administered by an invasive route such as by injection. Infurther embodiments, the polypeptide or polypeptides is administeredintravenously, subcutaneously, intramuscularly, intraarterially,intratumorally, or by inhalation, aerosol delivery.

The pharmaceutical compositions disclosed herein may also beadministered by infusion. Examples of well-known implants and modulesform administering pharmaceutical compositions include: U.S. Pat. No.4,487,603, which discloses an implantable micro-infusion pump fordispensing medication at a controlled rate; U.S. Pat. No. 4,447,233,which discloses a medication infusion pump for delivering medication ata precise infusion rate; U.S. Pat. No. 4,447,224, which discloses avariable flow implantable infusion apparatus for continuous drugdelivery; U.S. Pat. No. 4,439,196, which discloses an osmotic drugdelivery system having multi-chamber compartments. Many other suchimplants, delivery systems, and modules are well known to those skilledin the art.

Alternatively, one may administer the polypeptide or polypeptides in alocal rather than systemic manner, for example, via injection of theantibody directly into an arthritic joint or pathogen-induced lesioncharacterized by immunopathology, often in a depot or sustained releaseformulation. Furthermore, one may administer the polypeptide orpolypeptides in a targeted drug delivery system, for example, in aliposome coated with a tissue-specific antibody, targeting, for example,arthritic joint or pathogen-induced lesion characterized byimmunopathology. The liposomes will be targeted to and taken upselectively by the afflicted tissue.

The administration regimen depends on several factors, including,without limitation, the age, weight, and physical condition of thecanine being treated, the serum or tissue turnover rate of thetherapeutic antibody, the level of symptoms, the immunogenicity of thetherapeutic polypeptide or polypeptides, and the accessibility of thetarget cells in the biological matrix. Preferably, the administrationregimen delivers sufficient therapeutic polypeptide or polypeptides toeffect improvement in the target disease state, while simultaneouslyminimizing undesired side effects. Accordingly, the amount of biologicdelivered depends in part on the particular therapeutic polypeptide orpolypeptides and the severity of the condition being treated. Guidancein selecting appropriate doses of therapeutic antibodies is available(see, e.g., Wawrzynczak Antibody Therapy, Bios Scientific Pub. Ltd,Oxfordshire, U K (1996); Milgrom et al. New Engl. J. Med. 341:1966-1973(1999); Slamon et al. New Engl. J. Med. 344:783-792 (2001);Beniaminovitz et al. New Engl. J. Med. 342:613-619 (2000); Ghosh et al.New Engl. J. Med. 348:24-32 (2003); Lipsky et al. New Engl. J. Med.343:1594-1602 (2000)).

Determination of the appropriate dose of the polypeptide or polypeptidesis made by one skilled in the art, e.g., using parameters or factorsknown or suspected in the art to affect treatment. Generally, the dosebegins with an amount somewhat less than the optimum dose and it isincreased by small increments thereafter until the desired or optimumeffect is achieved relative to any negative side effects. Importantdiagnostic measures include those of symptoms of, e.g., the inflammationor level of inflammatory cytokines produced.

Nucleic Acids, Vectors, Host Cells, and Methods of Making

The disclosure also encompasses nucleic acid or nucleic acids encodingthe polypeptide or polypeptides described herein, a vector or vectorscomprising the nucleic acid or nucleic acids, and host cells comprisingthe nucleic acid or nucleic acids or the vector or vectors.

The polypeptide or polypeptides described herein may be produced inbacterial or eukaryotic cells. Some polypeptides, e.g., Fab's, can beproduced in bacterial cells, e.g., E. coli cells. Polypeptides can alsobe produced in eukaryotic cells such as transformed cell lines (e.g.,CHO, 293E, COS, 293T, Hela). In addition, polypeptides (e.g., scFv's)can be expressed in a yeast cell such as Pichia (see, e.g., Powers etal., J Immunol Methods. 251:123-35 (2001)), Hanseula, or Saccharomyces.To produce the antibody of interest, a polynucleotide or polynucleotidesencoding the polypeptide or polypeptides is/are constructed, introducedinto an expression vector or expression vectors, and then expressed insuitable host cells. To improve expression, the nucleotide sequences ofthe genes can be recoded without changing (or minimally changing—e.g.,removal of a C-terminal residue of the heavy or light chain) the aminoacid sequence. The areas for potential recoding include those associatedwith translation initiation, codon usage, and possible unintended mRNAsplicing. Polynucleotides encoding an Fc region variant described hereinwould be readily envisioned by the ordinarily skilled artisan.

Standard molecular biology techniques can be used to prepare therecombinant expression vector(s), transfect the host cells, select fortransformants, culture the host cells, and recover the polypeptide(e.g., antibody).

If the polypeptide or polypeptides is to be expressed in bacterial cells(e.g., E. coli), the expression vector should have characteristics thatpermit amplification of the vector in the bacterial cells. Additionally,when E. coli such as JM109, DH5α, HB101, or XL1-Blue is used as a host,the vector must have a promoter, for example, a lacZ promoter (Ward etal., 341:544-546 (1989), araB promoter (Better et al., Science,240:1041-1043 (1988)), or T7 promoter that can allow efficientexpression in E. coli. Examples of such vectors include, for example,M13-series vectors, pUC-series vectors, pBR322, pBluescript, pCR-Script,pGEX-5X-1 (Pharmacia), “QlAexpress system” (QIAGEN), pEGFP, and pET(when this expression vector is used, the host is preferably BL21expressing T7 RNA polymerase). The expression vector may contain asignal sequence for antibody secretion. For production into theperiplasm of E. coli, the pelB signal sequence (Lei et al., J.Bacteriol., 169:4379 (1987)) may be used as the signal sequence forantibody secretion. For bacterial expression, calcium chloride methodsor electroporation methods may be used to introduce the expressionvector into the bacterial cell.

If the polypeptide or polypeptides is to be expressed in animal cellssuch as CHO, COS, and NIH3T3 cells, the expression vector includes apromoter necessary for expression in these cells, for example, an SV40promoter (Mulligan et al., Nature, 277:108 (1979)) (e.g., early simianvirus 40 promoter), MMLV-LTR promoter, EF1α promoter (Mizushima et al.,Nucleic Acids Res., 18:5322 (1990)), or CMV promoter (e.g., humancytomegalovirus immediate early promoter). In addition to the nucleicacid sequence encoding the Fc region variant, the recombinant expressionvectors may carry additional sequences, such as sequences that regulatereplication of the vector in host cells (e.g., origins of replication)and selectable marker genes. The selectable marker gene facilitatesselection of host cells into which the vector has been introduced (seee.g., U.S. Pat. Nos. 4,399,216, 4,634,665 and 5,179,017). For example,typically the selectable marker gene confers resistance to drugs, suchas G418, hygromycin, or methotrexate, on a host cell into which thevector has been introduced. Examples of vectors with selectable markersinclude pMAM, pDR2, pBK-RSV, pBK-CMV, pOPRSV, and pOP13.

In some embodiments, the polypeptide or polypeptides are produced inmammalian cells. Exemplary mammalian host cells for expressingpolypeptide or polypeptides include Chinese Hamster Ovary (CHO cells)(including dhfr—CHO cells, described in Urlaub and Chasin (1980) Proc.Natl. Acad. Sci. USA 77:4216-4220, used with a DHFR selectable marker,e.g., as described in Kaufman and Sharp (1982) Mol. Biol. 159:601 621),human embryonic kidney 293 cells (e.g., 293, 293E, 293T), COS cells,NIH3T3 cells, lymphocytic cell lines, e.g., NS0 myeloma cells and SP2cells, and a cell from a transgenic animal, e.g., a transgenic mammal.For example, the cell is a mammary epithelial cell.

In an exemplary system for antibody expression, a recombinant expressionvector encoding both the antibody heavy chain and the antibody lightchain of the antibody is introduced into dhfr— CHO cells by calciumphosphate-mediated transfection. Within the recombinant expressionvector, the antibody heavy and light chain genes are each operativelylinked to enhancer/promoter regulatory elements (e.g., derived fromSV40, CMV, adenovirus and the like, such as a CMV enhancer/AdMLPpromoter regulatory element or an SV40 enhancer/AdMLP promoterregulatory element) to drive high levels of transcription of the genes.The recombinant expression vector also carries a DHFR gene, which allowsfor selection of CHO cells that have been transfected with the vectorusing methotrexate selection/amplification. The selected transformanthost cells are cultured to allow for expression of the antibody heavyand light chains and the antibody is recovered from the culture medium.

Methods of Treatment

The polypeptide or polypeptides disclosed herein can be used to treat orprevent any disease or disorder in a dog in need thereof. This inventionis particularly helpful in the treatment of chronic conditions whererepeated dosing is required. Because of the increased half-life of theprotein therapeutic, less frequent dosing and/or reduced dose levels maybe possible.

In some embodiments, the disease, disorder, condition or symptoms beingtreated or prevented is an allergic disease, a chronic pain, an acutepain, an inflammatory disease, an autoimmune disease, an endocrinedisease, a gastrointestinal disease, a skeletal/musculosceletal disease,a cardiovascular disease, a neurological disease, a renal disease, ametabolic disease, a immunological disease, a genetic/inherited disease,a fertility related disorder, an infectious disease or a cancer. Incertain embodiments, the disease or disorder being treated or preventedis atopic dermatitis, allergic dermatitis, food allergy, osteoarthriticpain, perioperative pain, dental pain, cancer pain, arthritis, anemia,obesity, or diabetes.

Antibodies may not only be used to treat or prevent disease but alsomodulate normal biological function for example manage fertility orbehavior.

Diagnosis

The polypeptide or polypeptides disclosed herein can also be used forvarious diagnostic purpose, for example, to determine whether a dog hasany particular disease or disorder. In some embodiments, the polypeptideor polypeptides may comprise a binding domain. The binding domain canspecifically bind to a protein, subunit, domain, motif, and/or epitopeas described herein (e.g., a maker for cancer cells). In someembodiments the polypeptide or polypeptides further comprises a labelinggroup. In general, label groups fall into a variety of classes,depending on the assay in which they are to be detected: a) isotopiclabels, which may be radioactive or heavy isotopes; b) magnetic labels(e.g., magnetic particles); c) redox active moieties; d) optical dyes;enzymatic groups (e.g. horseradish peroxidase, (3-galactosidase,luciferase, alkaline phosphatase); e) biotinylated groups; and f)predetermined polypeptide epitopes recognized by a secondary reporter(e.g., leucine zipper pair sequences, binding sites for secondaryantibodies, metal binding domains, epitope tags, etc.). In someembodiments, the labelling group is coupled to the antibody via spacerarms of various lengths to reduce potential steric hindrance. Variousmethods for labelling proteins are known in the art and may be used inperforming the present invention.

In some embodiments, the labeling group is a probe, a dye (e.g., afluorescent dye), or a radioactive isotope (e.g., ³H, ¹⁴C, ²²Na, ³⁶Cl,³⁵S, ³³P, or ¹²⁵I).

Specific labels can also include optical dyes, including, but notlimited to, chromophores, phosphors and fluorophores, with the latterbeing specific in many instances. Fluorophores can be either “smallmolecule” fluores, or proteinaceous fluores.

The fluorescent label can be any molecule that may be detected via itsinherent fluorescent properties. Suitable fluorescent labels include,but are not limited to, fluorescein, rhodamine, tetramethylrhodamine,eosin, erythrosin, coumarin, methyl-coumarins, pyrene, Malacite green,stilbene, Lucifer Yellow, Cascade BlueJ, Texas Red, IAEDANS, EDANS,BODIPY FL, LC Red 640, Cy 5, Cy 5.5, LC Red 705, Oregon green, theAlexa-Fluor dyes (Alexa Fluor 350, Alexa Fluor 430, Alexa Fluor 488,Alexa Fluor 546, Alexa Fluor 568, Alexa Fluor 594, Alexa Fluor 633,Alexa Fluor 660, Alexa Fluor 680), Cascade Blue, Cascade Yellow andR-phycoerythrin (PE) (Molecular Probes, Eugene, Oreg.), FITC, Rhodamine,and Texas Red (Pierce, Rockford, Ill.), Cy5, Cy5.5, Cy7 (Amersham LifeScience, Pittsburgh, Pa.). Suitable optical dyes, includingfluorophores, are described in Molecular Probes Handbook by Richard P.Haugland, which is incorporated by reference in its entirety.

Suitable proteinaceous fluorescent labels also include, but are notlimited to, green fluorescent protein, including a Renilla, Ptilosarcus,or Aequorea species of GFP (Chalfie et al., 1994, Science 263:802-805),EGFP (Clontech Laboratories, Inc., Genbank Accession Number U55762),blue fluorescent protein (BFP, Quantum Biotechnologies, Inc. 1801 deMaisonneuve Blvd. West, 8th Floor, Montreal, Quebec, Canada H3H1J9;Stauber, 1998, Biotechniques 24:462-471; Heim et al., 1996, Curr. Biol.6:178-182), enhanced yellow fluorescent protein (EYFP, ClontechLaboratories, Inc.), luciferase (Ichiki et al., 1993, J. Immunol.150:5408-5417), β galactosidase (Nolan et al., 1988, Proc. Natl. Acad.Sci. U.S.A. 85:2603-2607) and Renilla (WO92/15673, WO95/07463,WO98/14605, WO98/26277, WO99/49019, U.S. Pat. Nos. 5,292,658, 5,418,155,5,683,888, 5,741,668, 5,777,079, 5,804,387, 5,874,304, 5,876,995,5,925,558). All of the above-cited references in this paragraph areexpressly incorporated herein by reference in the entirety.

Assays FcγRI Binding:

Binding to FcγRI is a measure of the ability of an antibody to mediateADCC. In order to assess this property for an antibody an assay tomeasure binding of the antibody to FcγRI can be conducted using methodsknown in the art.

C1q Binding:

Binding to the first component of complement, C1q, is a measure of theability of an antibody to mediate complement-dependent cytotoxicity(CDC). In order to assess this property for an antibody, an assay tomeasure binding of the antibody to C1q can be conducted using methodsknown in the art.

Half-Life:

Methods of measuring half-life of an antibody is well known in the art.See, e.g., Booth et al., MAbs, 10(7):1098-1110 (2018). As an example,the half-life of an antibody can be measured by injection of theantibody into an animal model and measuring levels of the antibody inthe serum over a certain period of time. Exemplary animal models includenon-human primate models and transgenic mouse models. The transgenicmouse models (e.g. Tg32 or Tg276 transgenic mice) can be null for mouseFcRn alpha chain and express the human FcRn alpha transgene (e.g. underthe control of a constitutive promoter). The human FcRn alpha chain canpair in vivo with the mouse β2-microglobulin protein forming afunctional chimeric FcRn heterodimer.

EXAMPLES Example 1: Alanine Scanning Mutagenesis of CH2 and CH3 Domainsof Canine IgG.B

Alanine scanning mutagenesis (Morrison and Weiss, Curr. Opin. Chem.Biol. 5: 302-307 (2001)) was completed on residues 250, 251, 252, 254,256, 285, 286, 307, 309, 311, 315 in the CH₂ domain and residues 378,380, 428, 430, 433, 434, 435, and 436 in the CH₃ domain. For thisexperiment, the wild-type (wt) sequence of the CH₂ and CH₃ domains ofcanine IgG.B was synthesized and used as template for the mutagenesis.Each specified position with the exception of position 254 wasindividually changed to alanine by PCR mutagenesis using a primerencoding the change. Position 254 is alanine in the wild-type sequence,and it was modified to serine. The PCR product was subcloned into theGenScript FASEBA plasmid, transformed into E. coli and sequence verifiedfor the presence of the variant. Upstream of the CH2 domain is the SASA(single-domain antibody against serum albumin) tag (See, e.g. US2013/0129727A1) which has pM affinity for albumin. The PelB (pectatelyase B) signal peptide is at the N-terminus to facilitate secretion ofthe Fc into the medium. The expression of CH2-CH3 protein was regulatedby the Lac promoter. The supernatants from conditioned medium wereanalyzed for binding to canine FcRn (UniProtKB—E2R0L6 [FcRn] andUniProtKB—E2RN10 [canine beta-2-microglobulin]) at pH 5.5 using surfaceplasmon resonance (SPR).

For the SPR analyses using Biacore 8K, bovine serum albumin (BSA) wasimmobilized to CM5 sensor chip. The sensor chip surface of flow cells 1and 2 were activated by freshly mixed 50 mmol/L N-Hydroxysuccinimide and200 mmol/L 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloridefor 420 s (10 μL/min). Afterwards, BSA diluted in 10 mM sodium acetate(pH 4.5) was injected into the flow cell 2 to achieve conjugation, whileflow cell 1 was set as blank. After the amine coupling reaction, theremaining active coupling sites on chip surface were blocked with 420 sinjection of 1 mM ethanolamine hydrochloride. The running buffer for thebinding experiment was HBS-EP (10 mM HEPES, 500 mM NaCl, 3 mM EDTA,0.05% Tween 20, pH 5.5) and it was run at 25° C. Supernatants from thealanine variants were injected over chip surface and captured via theSASA tag onto the immobilized BSA for 60 sec. Canine FcRn at 400 nM wasinjected for 120 sec and the dissociation was complete with runningbuffer for 120 sec. The flow rate for the immobilization phase of BSAwas 10 μl/min and the flow rate for the association and dissociationphase was 30 μl/min. All of the data was processed using the Biacore 8Kevaluation software version 1.1. The tabulated data is shown in Table 3with the last column containing the average KD of wild-type divided bythe variant KD. The sensorgrams are shown in FIGS. 7A-7U.

TABLE 3 WT KD Avg/ Variant Variant ka (1/Ms) kd (1/s) KD (M) Comments KDT250A 1.86E+07 6.24E+00 3.35E−07 1.69 T250A 3.87E+06 1.27E+00 3.28E−071.72 L251A No Binding L251A No Binding L252A 3.32E+05 9.69E−02 2.92E−071.94 L252A 2.36E+06 5.67E−01 2.40E−07 2.36 A254S 7.91E+06 2.69E+003.40E−07 1.66 A254S 2.39E+06 7.58E−01 3.17E−07 1.78 T256A 3.71E+051.66E−01 4.47E−07 1.27 T256A 2.43E+08 7.24E+01 2.98E−07 1.90 Q285A3.28E+05 1.12E−01 3.41E−07 1.66 Q285A 1.37E+08 3.52E+01 2.57E−07 2.20T286A 4.22E+05 1.96E−01 4.64E−07 1.22 T286A 5.33E+05 3.04E−01 5.69E−070.99 P307A 2.87E+08 9.31E+01 3.25E−07 1.74 P307A 3.66E+06 1.23E+003.38E−07 1.67 I308A 3.57E+05 1.69E−01 4.72E−07 1.20 I308A 3.45E+051.94E−01 5.63E−07 1.00 G309A 1.42E+06 3.48E−01 2.45E−07 2.31 G309A2.44E+05 7.19E−02 2.94E−07 1.92 Q311A 2.43E+06 8.94E−01 3.68E−07 1.54Q311A 1.34E+06 4.96E−01 3.70E−07 1.53 K315A 4.13E+07 1.74E+01 4.22E−071.34 K315A 2.45E+05 1.34E−01 5.48E−07 1.03 D378A 2.72E+05 1.83E−016.73E−07 0.84 D378A 3.06E+05 1.81E−01 5.92E−07 0.96 E380A 2.41E+051.80E−01 7.47E−07 0.76 E380A 5.98E+05 3.69E−01 6.18E−07 0.92 M428A2.34E+05 1.69E−01 7.23E−07 0.78 M428A 3.18E+05 5.32E−01 1.67E−06 0.34E430A No Binding E430A No Binding H433A 8.62E+05 2.29E−01 2.66E−07 2.13H433A 2.78E+05 9.97E−02 3.59E−07 1.58 N434A 5.18E+05 2.37E−01 4.57E−071.24 N434A 9.66E+05 4.77E−01 4.94E−07 1.14 H435A No Binding H435A NoBinding Y436A 1.04E+06 4.07E−01 3.93E−07 1.44 Y436A 2.44E+05 2.13E−018.76E−07 0.65 Wild Type 3.61E+06 1.16E+00 3.21E−07 1.76 Wild Type6.32E+05 3.75E−01 5.92E−07 0.96 Wild Type 4.42E+05 1.85E−01 4.18E−071.35 Wild Type 5.87E+05 3.14E−01 5.34E−07 1.06 Wild Type 3.86E+051.88E−01 4.88E−07 1.16 Wild Type 3.91E+05 2.01E−01 5.14E−07 1.10 WildType 2.65E+05 1.60E−01 6.06E−07 0.93 Wild Type 3.10E+05 1.52E−014.89E−07 1.16 Wild Type 2.69E+05 1.66E−01 6.16E−07 0.92 Wild Type7.80E+05 4.79E−01 6.14E−07 0.92 Wild Type 2.90E+05 1.35E−01 4.65E−071.22 Wild Type 1.73E+05 1.96E−01 1.13E−06 0.50 WT KD 5.66E−07 Avg

Example 2: Generation of NNK Saturation Mutagenesis Libraries atSelected Positions and Analysis of Individual Variants

The NNK saturation mutagenesis method is an effective strategy togenerate all 20 possible amino acids at a desired position (Hogrefe etal., Biotechniques. 33: 1158-1165 (2002)). Individual NNK libraries atpositions 250, 252, 254, 309, 311, 378, 380, and 434 (EU numbering) weregenerated. For this method, NNK (N=A/C/G/T, K=G/T) primers at thespecified position were used with the QuikChange Site-DirectedMutagenesis Kit (Agilent). The supernatants from ninety individualtransformants from each library were assayed for binding to canine FcRnat pH 5.5 using the Biacore method described in Example 1. The onlydifference was the concentration of canine FcRn used in the assay was200 nM not 400 nM. The sensorgrams for all of the NNK library variantsare shown in FIGS. 8A-15F.

For the NNK library at position 250, none of the variants showedincreased binding to canine FcRn at pH 5.5. The data from variants T250Eand T250Q and wild type Fc are shown in Table 4. In a competitivebinding assay, variants T250E and T250Q in human IgG2 have beendemonstrated to bind tighter to human FcRn at pH 6.0 compared towild-type human IgG2 Fc (Hinton et al., J. Biol. Chem. 279: 6213-6216(2004)).

TABLE 4 Variant ka (1/Ms) kd (1/s) KD (M) T250Q 9.96E+04 2.58E−012.59E−06 T250Q 9.43E+04 2.68E−01 2.84E−06 T250E 1.14E+05 2.84E−012.48E−06 T250E 1.72E+05 2.87E−01 1.66E−06 WT 3.87E+04 3.47E−01 8.99E−06WT 1.14E+05 3.54E−01 3.11E−06

For the NNK library at position 252, only variants L252Y and L252M hadan apparent higher affinity for canine FcRn at pH 5.5 (see Table 5below). In the 90 transformants, there were no L252F variants present sono binding data was obtained with this variant.

TABLE 5 Variant ka (1/Ms) kd (1/s) KD (M) L252Y 4.02E+05 3.97E−029.87E−08 L252Y 3.58E+05 4.10E−02 1.14E−07 L252M 1.93E+05 1.68E−018.69E−07 L252M 2.18E+05 1.69E−01 7.74E−07 WT 1.68E+05 2.88E−01 1.71E−06WT 1.23E+05 3.26E−01 2.66E−06

For the NNK library at position 254, none of the variants tested had anapparent higher affinity for canine FcRn at pH 5.5. Data for the A254Tvariant is shown in Table 6 and the corresponding variant in human IgG1has been used in the YTE variant (M252Y/S254T/T256E) which has anincreased affinity to human FcRn at pH 6.0 (Dall'Acqua et al., J.Immunol. 169: 5171-5180 (2002)) and been demonstrated to increase thehalf-life of human IgG in preclinical models as well as in humans(Borrok et al., J. Biol. Chem. 290: 4282-4290 (2015); Robbie et al.,Antimicrob. Agents Ch. 57: 6147-6153 (2013)). In the 90 transformants,there were no A254H variants present so no data was obtained with thisvariant.

TABLE 6 Variant ka (1/Ms) kd (1/s) KD (M) A254T 1.63E+05 3.75E−012.29E−06 A254T 3.23E+05 4.33E−01 1.34E−06 WT 1.51E+05 3.10E−01 2.05E−06WT 1.05E+05 3.15E−01 2.99E−06

For the NNK libraries at positions 309 and 311, none of the variantstested had an apparent higher affinity for canine FcRn at pH 5.5. Datafor the variants G309P and Q311V are shown in Tables 7 and 8 and thecorresponding human variants (L309P and Q311V) in human IgG1 in severalcombinations with other variants have been demonstrated to have a higheraffinity for human FcRn at pH 6.0 (Dall'Acqua et al., J. Immunol. 169:5171-5180 (2002); Booth et al., MAbs, 10(7):1098-1110 (2018)). Thevariants G309D, G309K and Q311D were not identified in the NNK librariesand therefore were not tested for FcRn binding.

TABLE 7 Variant ka (1/Ms) kd (1/s) KD (M) G309P 3.77E+05 2.39E−016.35E−07 G309P 5.58E+05 2.42E−01 4.34E−07 G309P 2.07E+05 1.32E−016.37E−07 G309P 2.02E+05 1.45E−01 7.18E−07 WT 2.37E+05 2.10E−01 8.84E−07WT 2.53E+05 2.18E−01 8.62E−07

TABLE 8 Variant ka (1/Ms) kd (1/s) KD (M) Q311V 1.52E+06 5.66E−013.72E−07 Q311V 1.59E+06 6.96E−01 4.39E−07 WT 2.67E+05 1.70E−01 6.39E−07WT 2.47E+05 1.71E−01 6.92E−07

For the NNK libraries at positions 378 and 380, none of the variantstested had an apparent higher affinity for canine FcRn at pH 5.5. Thedata for variant D378V is shown in Table 9 and the corresponding variantin human IgG1 has been used in combinations with other IgG variants todemonstrate higher affinity to human FcRn at pH 6.0 compared towild-type Fc and extending the half-life of human IgG in transgenichuman FcRn mice (Monnet et al., MAB S. 6: 422-436 (2014); Booth et al.,2018). Also, the data for variant E380A is shown in Table 10 and thecorresponding variant in human IgG has been shown to have higher bindingaffinity to human FcRn at pH 6.0 (Shields et al., J. Biol. Chem. 276:6591-6604 (2001)). Variants D378E, D378I, D378K, and E380F were notpresent in the NNK libraries and not screened for binding to canineFcRn.

TABLE 9 Variant ka (1/Ms) kd (1/s) KD (M) D378V 2.29E+05 1.59E−016.93E−07 D378V 1.84E+05 1.60E−01 8.73E−07 WT 3.36E+05 1.69E−01 5.02E−07WT 2.64E+05 2.07E−01 7.84E−07

TABLE 10 Variant ka (1/Ms) kd (1/s) KD (M) E380A 1.68E+05 2.23E−011.32E−06 E380A 1.52E+05 2.39E−01 1.57E−06 WT 1.15E+05 1.79E−01 1.56E−06WT 2.42E+05 1.82E−01 7.54E−07

For the NNK library at position 434, variants N434Y, N434W, and N434Rhad a higher affinity for canine FcRn at pH 5.5 shown in Table 11.Variants N434S and N434A did not have a higher affinity for canine FcRnat a low pH which is unlike the corresponding human IgG1 variants(Petkova et al., Int. Immunol. 18: 1759-1769 (2006); Yeung et al., J.Immunol. 182: 7663-7671 (2009); Zalevsky et al., Nat. Biotechnol. 28:157-159 (2010); Deng et al., Drug Metab. Dispos. 38: 600-605 (2010)).The NNK library screened at position 434 did not contain the N434Fvariant so the binding of this variant to canine FcRn was not tested.

TABLE 11 Variant ka (1/Ms) kd (1/s) KD (M) N434Y 6.07E+05 9.68E−031.59E−08 N434W 6.93E+05 2.80E−02 4.04E−08 N434W 4.20E+06 3.18E−017.57E−08 N434R 4.88E+05 5.24E−02 1.07E−07 N434R 3.99E+05 6.33E−021.59E−07 N434S 2.25E+05 2.07E−01 9.24E−07 N434S 1.99E+05 2.09E−011.05E−06 N434A 2.72E+05 1.56E−01 5.73E−07 N434A 2.61E+05 1.64E−016.29E−07 WT 1.90E+05 1.81E−01 9.55E−07 WT 1.59E+05 2.09E−01 1.31E−06

Example 3: Binding Kinetics for L252Y, N434Y, N434W, N434R, N434H andYTE (L252Y/A254T/T256E) Variants and Wild-Type Fc

Several canine IgG.B variants that demonstrated higher affinity tocanine FcRn at pH 5.5 were further evaluated for binding kinetics tocanine FcRn. In this study, the binding of the variants (L252Y, N434Y,N434W, N434R, N434H), YTE variant (L252Y/A254T/T256E) and wild-typecanine Fc to canine FcRn at pH 5.5 and pH 7.4 was evaluated. The Biacoremethod for the pH 5.5 condition was the same as described in Example 1with the exception that four concentrations of FcRn (100 nM, 200 nM, 400nM, 800 nM) were tested which yields more precise binding kinetics. Forthe Biacore conditions at pH 7.4, the running buffer used was 10 mMHEPES, 500 mM NaCl, 3 mM EDTA, 0.05% Tween 20, pH 7.4 and theconcentration of canine FcRn tested was 200 nM. All of the variantsincluding YTE and wild type did not bind to canine FcRn at pH 7.4. Thebinding kinetics at pH 5.5 are shown in Table 12 and the sensorgrams areshown in FIGS. 16A-16E. The variants tested showed increased affinityfor canine FcRn at pH 5.5 as compared to wild type Fc.

TABLE 12 Variant ka (1/Ms) kd (1/s) KD (M) L252Y 2.75E+05 4.76E−021.73E−07 N434Y 5.20E+05 1.51E−02 2.91E−08 N434W 4.46E+05 4.50E−021.01E−07 N434R 4.40E+05 8.01E−02 1.82E−07 N434H 4.11E+05 1.02E−012.47E−07 Wild Type 1.68E+05 5.27E−01 3.15E−06 YTE 2.50E+05 4.60E−021.84E−07

OTHER EMBODIMENTS

While the invention has been described in conjunction with the detaileddescription thereof, the foregoing description is intended to illustrateand not limit the scope of the invention, which is defined by the scopeof the appended claims. Other aspects, advantages, and modifications arewithin the scope of the following claims.

1-43. (canceled)
 44. A polypeptide comprising a canine IgG Fc regionvariant, or a canine FcRn-binding region thereof, wherein the canine IgGFc region variant or the canine FcRn-binding region thereof is differentfrom a wild type canine IgG Fc region or a canine FcRn-binding regionthereof by no more than one amino acid, wherein the one amino aciddifference is His at a position that corresponds to amino acid position434 of the wild type canine IgG Fc region, wherein the amino acidposition is based on EU numbering, and wherein the polypeptide hasincreased binding affinity to canine FcRn when compared to a controlpolypeptide, wherein the control polypeptide is identical to thepolypeptide except for having the wild type canine IgG Fc region or aFcRn-binding region thereof in place of the canine IgG Fc region variantor the canine FcRn-binding region thereof.
 45. The polypeptide of claim44, wherein the polypeptide further comprises a binding domain.
 46. Thepolypeptide of claim 45, wherein the binding domain comprises (i) sixcomplementarity determining regions (CDRs) of an immunoglobulinmolecule; (ii) a ligand binding domain of a canine receptor protein,(iii) a nanobody or (iv) an extracellular domain of a canine receptorprotein.
 47. The polypeptide of claim 45, wherein the binding domainspecifically binds to an antigen selected from the group consisting ofNGF, TrKA, ADAMTS, IL-1, IL-2, IL-4, IL-4R, Angiotensin type 1 (AT1)receptor, Angiotensin type 2 (AT2) receptor, IL-5, IL-12, IL-13, IL-31,IL-33, CD3, CD20, CD47, CD52, and complement system complex.
 48. Thepolypeptide of claim 44, further comprising a protein selected from thegroup consisting of EPO, CTLA4, LFA3, VEGFR1NEGFR3, IL-1 R, IL-4R, GLP-1receptor agonist, and Thrombopoietin binding peptide.
 49. Thepolypeptide of claim 44, wherein the polypeptide binds to a canine FcRnat a higher level at pH 5.5 than at pH 7.4.
 50. A pharmaceuticalcomposition comprising (i) the polypeptide of claim 44, and (ii) apharmaceutically acceptable excipient.
 51. A polypeptide comprising acanine IgG Fc region variant, or a canine FcRn-binding region thereof,wherein the canine IgG Fc region variant or the canine FcRn-bindingregion thereof comprises: (i) Met at a position that corresponds toamino acid position 252 of the wild type canine IgG Fc region; and (ii)His at a position that corresponds to amino acid position 434 of thewild type canine IgG Fc region, wherein the amino acid position is basedon EU numbering, and wherein the polypeptide has increased bindingaffinity to canine FcRn when compared to a control polypeptide, whereinthe control polypeptide is identical to the polypeptide except forhaving the wild type canine IgG Fc region or a FcRn-binding regionthereof in place of the canine IgG Fc region variant or the canineFcRn-binding region thereof.
 52. The polypeptide of claim 51, whereinthe polypeptide further comprises a binding domain.
 53. The polypeptideof claim 52, wherein the binding domain comprises (i) six CDRs of animmunoglobulin molecule; (ii) a ligand binding domain of a caninereceptor protein, (iii) a nanobody or (iv) an extracellular domain of acanine receptor protein.
 54. The polypeptide of claim 52, wherein thebinding domain specifically binds to an antigen selected from the groupconsisting of NGF, TrKA, ADAMTS, IL-1, IL-2, IL-4, IL-4R, AT1 receptor,AT2 receptor, IL-5, IL-12, IL-13, IL-31, IL-33, CD3, CD20, CD47, CD52,and complement system complex.
 55. The polypeptide of claim 51, furthercomprising a protein selected from the group consisting of EPO, CTLA4,LFA3, VEGFR1NEGFR3, IL-1 R, IL-4R, GLP-1 receptor agonist, andThrombopoietin binding peptide.
 56. The polypeptide of claim 51, whereinthe polypeptide binds to a canine FcRn at a higher level at pH 5.5 thanat pH 7.4.
 57. A pharmaceutical composition comprising (i) thepolypeptide of claim 51, and (ii) a pharmaceutically acceptableexcipient.